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[vis.git] / sam.c

/*
 * Heavily inspired (and partially based upon) the X11 version of
 * Rob Pike's sam text editor originally written for Plan 9.
 *
 *  Copyright © 2016-2018 Marc André Tanner <mat at brain-dump.org>
 *  Copyright © 1998 by Lucent Technologies
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 *
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include "sam.h"
#include "vis-core.h"
#include "buffer.h"
#include "text.h"
#include "text-motions.h"
#include "text-objects.h"
#include "text-regex.h"
#include "util.h"

#define MAX_ARGV 8

typedef struct Address Address;
typedef struct Command Command;
typedef struct CommandDef CommandDef;

struct Change {
        enum ChangeType {
                TRANSCRIPT_INSERT = 1 << 0,
                TRANSCRIPT_DELETE = 1 << 1,
                TRANSCRIPT_CHANGE = TRANSCRIPT_INSERT|TRANSCRIPT_DELETE,
        } type;
        Win *win;          /* window in which changed file is being displayed */
        Selection *sel;    /* selection associated with this change, might be NULL */
        Filerange range;   /* inserts are denoted by zero sized range (same start/end) */
        const char *data;  /* will be free(3)-ed after transcript has been processed */
        size_t len;        /* size in bytes of the chunk pointed to by data */
        Change *next;      /* modification position increase monotonically */
        int count;         /* how often should data be inserted? */
};

struct Address {
        char type;      /* # (char) l (line) g (goto line) / ? . $ + - , ; % ' */
        Regex *regex;   /* NULL denotes default for x, y, X, and Y commands */
        size_t number;  /* line or character number */
        Address *left;  /* left hand side of a compound address , ; */
        Address *right; /* either right hand side of a compound address or next address */
};

typedef struct {
        int start, end; /* interval [n,m] */
        bool mod;       /* % every n-th match, implies n == m */
} Count;

struct Command {
        const char *argv[MAX_ARGV];/* [0]=cmd-name, [1..MAX_ARGV-2]=arguments, last element always NULL */
        Address *address;         /* range of text for command */
        Regex *regex;             /* regex to match, used by x, y, g, v, X, Y */
        const CommandDef *cmddef; /* which command is this? */
        Count count;              /* command count, defaults to [0,+inf] */
        int iteration;            /* current command loop iteration */
        char flags;               /* command specific flags */
        Command *cmd;             /* target of x, y, g, v, X, Y, { */
        Command *next;            /* next command in {} group */
};

struct CommandDef {
        const char *name;                    /* command name */
        VIS_HELP_DECL(const char *help;)     /* short, one-line help text */
        enum {
                CMD_NONE          = 0,       /* standalone command without any arguments */
                CMD_CMD           = 1 << 0,  /* does the command take a sub/target command? */
                CMD_REGEX         = 1 << 1,  /* regex after command? */
                CMD_REGEX_DEFAULT = 1 << 2,  /* is the regex optional i.e. can we use a default? */
                CMD_COUNT         = 1 << 3,  /* does the command support a count as in s2/../? */
                CMD_TEXT          = 1 << 4,  /* does the command need a text to insert? */
                CMD_ADDRESS_NONE  = 1 << 5,  /* is it an error to specify an address for the command? */
                CMD_ADDRESS_POS   = 1 << 6,  /* no address implies an empty range at current cursor position */
                CMD_ADDRESS_LINE  = 1 << 7,  /* if no address is given, use the current line */
                CMD_ADDRESS_AFTER = 1 << 8,  /* if no address is given, begin at the start of the next line */
                CMD_ADDRESS_ALL   = 1 << 9,  /* if no address is given, apply to whole file (independent of #cursors) */
                CMD_ADDRESS_ALL_1CURSOR = 1 << 10, /* if no address is given and only 1 cursor exists, apply to whole file */
                CMD_SHELL         = 1 << 11, /* command needs a shell command as argument */
                CMD_FORCE         = 1 << 12, /* can the command be forced with ! */
                CMD_ARGV          = 1 << 13, /* whether shell like argument splitting is desired */
                CMD_ONCE          = 1 << 14, /* command should only be executed once, not for every selection */
                CMD_LOOP          = 1 << 15, /* a looping construct like `x`, `y` */
                CMD_GROUP         = 1 << 16, /* a command group { ... } */
                CMD_DESTRUCTIVE   = 1 << 17, /* command potentially destroys window */
        } flags;
        const char *defcmd;                  /* name of a default target command */
        bool (*func)(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*); /* command implementation */
};

/* sam commands */
static bool cmd_insert(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_append(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_change(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_delete(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_guard(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_extract(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_select(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_print(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_files(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_pipein(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_pipeout(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_filter(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_launch(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_substitute(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_write(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_read(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_edit(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_quit(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_cd(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
/* vi(m) commands */
static bool cmd_set(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_open(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_qall(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_split(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_vsplit(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_new(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_vnew(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_wq(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_earlier_later(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_help(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_map(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_unmap(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_langmap(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);
static bool cmd_user(Vis*, Win*, Command*, const char *argv[], Selection*, Filerange*);

static const CommandDef cmds[] = {
        //      name            help
        //      flags, default command, implemenation
        {
                "a",            VIS_HELP("Append text after range")
                CMD_TEXT, NULL, cmd_append
        }, {
                "c",            VIS_HELP("Change text in range")
                CMD_TEXT, NULL, cmd_change
        }, {
                "d",            VIS_HELP("Delete text in range")
                CMD_NONE, NULL, cmd_delete
        }, {
                "g",            VIS_HELP("If range contains regexp, run command")
                CMD_COUNT|CMD_REGEX|CMD_CMD, "p", cmd_guard
        }, {
                "i",            VIS_HELP("Insert text before range")
                CMD_TEXT, NULL, cmd_insert
        }, {
                "p",            VIS_HELP("Create selection covering range")
                CMD_NONE, NULL, cmd_print
        }, {
                "s",            VIS_HELP("Substitute: use x/pattern/ c/replacement/ instead")
                CMD_SHELL|CMD_ADDRESS_LINE, NULL, cmd_substitute
        }, {
                "v",            VIS_HELP("If range does not contain regexp, run command")
                CMD_COUNT|CMD_REGEX|CMD_CMD, "p", cmd_guard
        }, {
                "x",            VIS_HELP("Set range and run command on each match")
                CMD_CMD|CMD_REGEX|CMD_REGEX_DEFAULT|CMD_ADDRESS_ALL_1CURSOR|CMD_LOOP, "p", cmd_extract
        }, {
                "y",            VIS_HELP("As `x` but select unmatched text")
                CMD_CMD|CMD_REGEX|CMD_ADDRESS_ALL_1CURSOR|CMD_LOOP, "p", cmd_extract
        }, {
                "X",            VIS_HELP("Run command on files whose name matches")
                CMD_CMD|CMD_REGEX|CMD_REGEX_DEFAULT|CMD_ADDRESS_NONE|CMD_ONCE, NULL, cmd_files
        }, {
                "Y",            VIS_HELP("As `X` but select unmatched files")
                CMD_CMD|CMD_REGEX|CMD_ADDRESS_NONE|CMD_ONCE, NULL, cmd_files
        }, {
                ">",            VIS_HELP("Send range to stdin of command")
                CMD_SHELL|CMD_ADDRESS_LINE, NULL, cmd_pipeout
        }, {
                "<",            VIS_HELP("Replace range by stdout of command")
                CMD_SHELL|CMD_ADDRESS_POS, NULL, cmd_pipein
        }, {
                "|",            VIS_HELP("Pipe range through command")
                CMD_SHELL, NULL, cmd_filter
        }, {
                "!",            VIS_HELP("Run the command")
                CMD_SHELL|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_launch
        }, {
                "w",            VIS_HELP("Write range to named file")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_ALL, NULL, cmd_write
        }, {
                "r",            VIS_HELP("Replace range by contents of file")
                CMD_ARGV|CMD_ADDRESS_AFTER, NULL, cmd_read
        }, {
                "{",            VIS_HELP("Start of command group")
                CMD_GROUP, NULL, NULL
        }, {
                "}",            VIS_HELP("End of command group" )
                CMD_NONE, NULL, NULL
        }, {
                "e",            VIS_HELP("Edit file")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE|CMD_DESTRUCTIVE, NULL, cmd_edit
        }, {
                "q",            VIS_HELP("Quit the current window")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE|CMD_DESTRUCTIVE, NULL, cmd_quit
        }, {
                "cd",           VIS_HELP("Change directory")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_cd
        },
        /* vi(m) related commands */
        {
                "help",         VIS_HELP("Show this help")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_help
        }, {
                "map",          VIS_HELP("Map key binding `:map <mode> <lhs> <rhs>`")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_map
        }, {
                "map-window",   VIS_HELP("As `map` but window local")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_map
        }, {
                "unmap",        VIS_HELP("Unmap key binding `:unmap <mode> <lhs>`")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_unmap
        }, {
                "unmap-window", VIS_HELP("As `unmap` but window local")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_unmap
        }, {
                "langmap",      VIS_HELP("Map keyboard layout `:langmap <locale-keys> <latin-keys>`")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_langmap
        }, {
                "new",          VIS_HELP("Create new window")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_new
        }, {
                "open",         VIS_HELP("Open file")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_open
        }, {
                "qall",         VIS_HELP("Exit vis")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_NONE|CMD_DESTRUCTIVE, NULL, cmd_qall
        }, {
                "set",          VIS_HELP("Set option")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_set
        }, {
                "split",        VIS_HELP("Horizontally split window")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_split
        }, {
                "vnew",         VIS_HELP("As `:new` but split vertically")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_vnew
        }, {
                "vsplit",       VIS_HELP("Vertically split window")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_vsplit
        }, {
                "wq",           VIS_HELP("Write file and quit")
                CMD_ARGV|CMD_FORCE|CMD_ONCE|CMD_ADDRESS_ALL|CMD_DESTRUCTIVE, NULL, cmd_wq
        }, {
                "earlier",      VIS_HELP("Go to older text state")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_earlier_later
        }, {
                "later",        VIS_HELP("Go to newer text state")
                CMD_ARGV|CMD_ONCE|CMD_ADDRESS_NONE, NULL, cmd_earlier_later
        },
        { NULL, VIS_HELP(NULL) CMD_NONE, NULL, NULL },
};

static const CommandDef cmddef_select = {
        NULL, VIS_HELP(NULL) CMD_NONE, NULL, cmd_select
};

/* :set command options */
typedef struct {
        const char *names[3];            /* name and optional alias */
        enum VisOption flags;            /* option type, etc. */
        VIS_HELP_DECL(const char *help;) /* short, one line help text */
        VisOptionFunction *func;         /* option handler, NULL for bulitins */
        void *context;                   /* context passed to option handler function */
} OptionDef;

enum {
        OPTION_SHELL,
        OPTION_ESCDELAY,
        OPTION_AUTOINDENT,
        OPTION_EXPANDTAB,
        OPTION_TABWIDTH,
        OPTION_SHOW_SPACES,
        OPTION_SHOW_TABS,
        OPTION_SHOW_NEWLINES,
        OPTION_SHOW_EOF,
        OPTION_NUMBER,
        OPTION_NUMBER_RELATIVE,
        OPTION_CURSOR_LINE,
        OPTION_COLOR_COLUMN,
        OPTION_SAVE_METHOD,
        OPTION_LOAD_METHOD,
        OPTION_CHANGE_256COLORS,
        OPTION_LAYOUT,
};

static const OptionDef options[] = {
        [OPTION_SHELL] = {
                { "shell" },
                VIS_OPTION_TYPE_STRING,
                VIS_HELP("Shell to use for external commands (default: $SHELL, /etc/passwd, /bin/sh)")
        },
        [OPTION_ESCDELAY] = {
                { "escdelay" },
                VIS_OPTION_TYPE_NUMBER,
                VIS_HELP("Milliseconds to wait to distinguish <Escape> from terminal escape sequences")
        },
        [OPTION_AUTOINDENT] = {
                { "autoindent", "ai" },
                VIS_OPTION_TYPE_BOOL,
                VIS_HELP("Copy leading white space from previous line")
        },
        [OPTION_EXPANDTAB] = {
                { "expandtab", "et" },
                VIS_OPTION_TYPE_BOOL,
                VIS_HELP("Replace entered <Tab> with `tabwidth` spaces")
        },
        [OPTION_TABWIDTH] = {
                { "tabwidth", "tw" },
                VIS_OPTION_TYPE_NUMBER,
                VIS_HELP("Number of spaces to display (and insert if `expandtab` is enabled) for a tab")
        },
        [OPTION_SHOW_SPACES] = {
                { "show-spaces" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display replacement symbol instead of a space")
        },
        [OPTION_SHOW_TABS] = {
                { "show-tabs" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display replacement symbol for tabs")
        },
        [OPTION_SHOW_NEWLINES] = {
                { "show-newlines" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display replacement symbol for newlines")
        },
        [OPTION_SHOW_EOF] = {
                { "show-eof" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display replacement symbol for lines after the end of the file")
        },
        [OPTION_NUMBER] = {
                { "numbers", "nu" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display absolute line numbers")
        },
        [OPTION_NUMBER_RELATIVE] = {
                { "relativenumbers", "rnu" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Display relative line numbers")
        },
        [OPTION_CURSOR_LINE] = {
                { "cursorline", "cul" },
                VIS_OPTION_TYPE_BOOL|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Highlight current cursor line")
        },
        [OPTION_COLOR_COLUMN] = {
                { "colorcolumn", "cc" },
                VIS_OPTION_TYPE_NUMBER|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Highlight a fixed column")
        },
        [OPTION_SAVE_METHOD] = {
                { "savemethod" },
                VIS_OPTION_TYPE_STRING|VIS_OPTION_NEED_WINDOW,
                VIS_HELP("Save method to use for current file 'auto', 'atomic' or 'inplace'")
        },
        [OPTION_LOAD_METHOD] = {
                { "loadmethod" },
                VIS_OPTION_TYPE_STRING,
                VIS_HELP("How to load existing files 'auto', 'read' or 'mmap'")
        },
        [OPTION_CHANGE_256COLORS] = {
                { "change-256colors" },
                VIS_OPTION_TYPE_BOOL,
                VIS_HELP("Change 256 color palette to support 24bit colors")
        },
        [OPTION_LAYOUT] = {
                { "layout" },
                VIS_OPTION_TYPE_STRING,
                VIS_HELP("Vertical or horizontal window layout")
        },
};

bool sam_init(Vis *vis) {
        if (!(vis->cmds = map_new()))
                return false;
        bool ret = true;
        for (const CommandDef *cmd = cmds; cmd && cmd->name; cmd++)
                ret &= map_put(vis->cmds, cmd->name, cmd);

        if (!(vis->options = map_new()))
                return false;
        for (int i = 0; i < LENGTH(options); i++) {
                for (const char *const *name = options[i].names; *name; name++)
                        ret &= map_put(vis->options, *name, &options[i]);
        }

        return ret;
}

const char *sam_error(enum SamError err) {
        static const char *error_msg[] = {
                [SAM_ERR_OK]              = "Success",
                [SAM_ERR_MEMORY]          = "Out of memory",
                [SAM_ERR_ADDRESS]         = "Bad address",
                [SAM_ERR_NO_ADDRESS]      = "Command takes no address",
                [SAM_ERR_UNMATCHED_BRACE] = "Unmatched `}'",
                [SAM_ERR_REGEX]           = "Bad regular expression",
                [SAM_ERR_TEXT]            = "Bad text",
                [SAM_ERR_SHELL]           = "Shell command expected",
                [SAM_ERR_COMMAND]         = "Unknown command",
                [SAM_ERR_EXECUTE]         = "Error executing command",
                [SAM_ERR_NEWLINE]         = "Newline expected",
                [SAM_ERR_MARK]            = "Invalid mark",
                [SAM_ERR_CONFLICT]        = "Conflicting changes",
                [SAM_ERR_WRITE_CONFLICT]  = "Can not write while changing",
                [SAM_ERR_LOOP_INVALID_CMD]  = "Destructive command in looping construct",
                [SAM_ERR_GROUP_INVALID_CMD] = "Destructive command in group",
                [SAM_ERR_COUNT]           = "Invalid count",
        };

        size_t idx = err;
        return idx < LENGTH(error_msg) ? error_msg[idx] : NULL;
}

static void change_free(Change *c) {
        if (!c)
                return;
        free((char*)c->data);
        free(c);
}

static Change *change_new(Transcript *t, enum ChangeType type, Filerange *range, Win *win, Selection *sel) {
        if (!text_range_valid(range))
                return NULL;
        Change **prev, *next;
        if (t->latest && t->latest->range.end <= range->start) {
                prev = &t->latest->next;
                next = t->latest->next;
        } else {
                prev = &t->changes;
                next = t->changes;
        }
        while (next && next->range.end <= range->start) {
                prev = &next->next;
                next = next->next;
        }
        if (next && next->range.start < range->end) {
                t->error = SAM_ERR_CONFLICT;
                return NULL;
        }
        Change *new = calloc(1, sizeof *new);
        if (new) {
                new->type = type;
                new->range = *range;
                new->sel = sel;
                new->win = win;
                new->next = next;
                *prev = new;
                t->latest = new;
        }
        return new;
}

static void sam_transcript_init(Transcript *t) {
        memset(t, 0, sizeof *t);
}

static bool sam_transcript_error(Transcript *t, enum SamError error) {
        if (t->changes)
                t->error = error;
        return t->error;
}

static void sam_transcript_free(Transcript *t) {
        for (Change *c = t->changes, *next; c; c = next) {
                next = c->next;
                change_free(c);
        }
}

static bool sam_insert(Win *win, Selection *sel, size_t pos, const char *data, size_t len, int count) {
        Filerange range = text_range_new(pos, pos);
        Change *c = change_new(&win->file->transcript, TRANSCRIPT_INSERT, &range, win, sel);
        if (c) {
                c->data = data;
                c->len = len;
                c->count = count;
        }
        return c;
}

static bool sam_delete(Win *win, Selection *sel, Filerange *range) {
        return change_new(&win->file->transcript, TRANSCRIPT_DELETE, range, win, sel);
}

static bool sam_change(Win *win, Selection *sel, Filerange *range, const char *data, size_t len, int count) {
        Change *c = change_new(&win->file->transcript, TRANSCRIPT_CHANGE, range, win, sel);
        if (c) {
                c->data = data;
                c->len = len;
                c->count = count;
        }
        return c;
}

static Address *address_new(void) {
        Address *addr = calloc(1, sizeof *addr);
        if (addr)
                addr->number = EPOS;
        return addr;
}

static void address_free(Address *addr) {
        if (!addr)
                return;
        text_regex_free(addr->regex);
        address_free(addr->left);
        address_free(addr->right);
        free(addr);
}

static void skip_spaces(const char **s) {
        while (**s == ' ' || **s == '\t')
                (*s)++;
}

static char *parse_until(const char **s, const char *until, const char *escchars, int type){
        Buffer buf;
        buffer_init(&buf);
        size_t len = strlen(until);
        bool escaped = false;

        for (; **s && (!memchr(until, **s, len) || escaped); (*s)++) {
                if (type != CMD_SHELL && !escaped && **s == '\\') {
                        escaped = true;
                        continue;
                }

                char c = **s;

                if (escaped) {
                        escaped = false;
                        if (c == '\n')
                                continue;
                        if (c == 'n') {
                                c = '\n';
                        } else if (c == 't') {
                                c = '\t';
                        } else if (type != CMD_REGEX && type != CMD_TEXT && c == '\\') {
                                // ignore one of the back slashes
                        } else {
                                bool delim = memchr(until, c, len);
                                bool esc = escchars && memchr(escchars, c, strlen(escchars));
                                if (!delim && !esc)
                                        buffer_append(&buf, "\\", 1);
                        }
                }

                if (!buffer_append(&buf, &c, 1)) {
                        buffer_release(&buf);
                        return NULL;
                }
        }

        buffer_terminate(&buf);

        return buffer_move(&buf);
}

static char *parse_delimited(const char **s, int type) {
        char delim[2] = { **s, '\0' };
        if (!delim[0] || isspace((unsigned char)delim[0]))
                return NULL;
        (*s)++;
        char *chunk = parse_until(s, delim, NULL, type);
        if (**s == delim[0])
                (*s)++;
        return chunk;
}

static int parse_number(const char **s) {
        char *end = NULL;
        int number = strtoull(*s, &end, 10);
        if (end == *s)
                return 0;
        *s = end;
        return number;
}

static char *parse_text(const char **s, Count *count) {
        skip_spaces(s);
        const char *before = *s;
        count->start = parse_number(s);
        if (*s == before)
                count->start = 1;
        if (**s != '\n') {
                before = *s;
                char *text = parse_delimited(s, CMD_TEXT);
                return (!text && *s != before) ? strdup("") : text;
        }

        Buffer buf;
        buffer_init(&buf);
        const char *start = *s + 1;
        bool dot = false;

        for ((*s)++; **s && (!dot || **s != '\n'); (*s)++)
                dot = (**s == '.');

        if (!dot || !buffer_put(&buf, start, *s - start - 1) ||
            !buffer_append(&buf, "\0", 1)) {
                buffer_release(&buf);
                return NULL;
        }

        return buffer_move(&buf);
}

static char *parse_shellcmd(Vis *vis, const char **s) {
        skip_spaces(s);
        char *cmd = parse_until(s, "\n", NULL, false);
        if (!cmd) {
                const char *last_cmd = register_get(vis, &vis->registers[VIS_REG_SHELL], NULL);
                return last_cmd ? strdup(last_cmd) : NULL;
        }
        register_put0(vis, &vis->registers[VIS_REG_SHELL], cmd);
        return cmd;
}

static void parse_argv(const char **s, const char *argv[], size_t maxarg) {
        for (size_t i = 0; i < maxarg; i++) {
                skip_spaces(s);
                if (**s == '"' || **s == '\'')
                        argv[i] = parse_delimited(s, CMD_ARGV);
                else
                        argv[i] = parse_until(s, " \t\n", "\'\"", CMD_ARGV);
        }
}

static bool valid_cmdname(const char *s) {
        unsigned char c = (unsigned char)*s;
        return c && !isspace(c) && !isdigit(c) && (!ispunct(c) || (c == '-' && valid_cmdname(s+1)));
}

static char *parse_cmdname(const char **s) {
        Buffer buf;
        buffer_init(&buf);

        skip_spaces(s);
        while (valid_cmdname(*s))
                buffer_append(&buf, (*s)++, 1);

        buffer_terminate(&buf);

        return buffer_move(&buf);
}

static Regex *parse_regex(Vis *vis, const char **s) {
        const char *before = *s;
        char *pattern = parse_delimited(s, CMD_REGEX);
        if (!pattern && *s == before)
                return NULL;
        Regex *regex = vis_regex(vis, pattern);
        free(pattern);
        return regex;
}

static enum SamError parse_count(const char **s, Count *count) {
        count->mod = **s == '%';

        if (count->mod) {
                (*s)++;
                int n = parse_number(s);
                if (!n)
                        return SAM_ERR_COUNT;
                count->start = n;
                count->end = n;
                return SAM_ERR_OK;
        }

        const char *before = *s;
        if (!(count->start = parse_number(s)) && *s != before)
                return SAM_ERR_COUNT;
        if (**s != ',') {
                count->end = count->start ? count->start : INT_MAX;
                return SAM_ERR_OK;
        } else {
                (*s)++;
        }
        before = *s;
        if (!(count->end = parse_number(s)) && *s != before)
                return SAM_ERR_COUNT;
        if (!count->end)
                count->end = INT_MAX;
        return SAM_ERR_OK;
}

static Address *address_parse_simple(Vis *vis, const char **s, enum SamError *err) {

        skip_spaces(s);

        Address addr = {
                .type = **s,
                .regex = NULL,
                .number = EPOS,
                .left = NULL,
                .right = NULL,
        };

        switch (addr.type) {
        case '#': /* character #n */
                (*s)++;
                addr.number = parse_number(s);
                break;
        case '0': case '1': case '2': case '3': case '4': /* line n */
        case '5': case '6': case '7': case '8': case '9':
                addr.type = 'l';
                addr.number = parse_number(s);
                break;
        case '\'':
                (*s)++;
                if ((addr.number = vis_mark_from(vis, **s)) == VIS_MARK_INVALID) {
                        *err = SAM_ERR_MARK;
                        return NULL;
                }
                (*s)++;
                break;
        case '/': /* regexp forwards */
        case '?': /* regexp backwards */
                addr.regex = parse_regex(vis, s);
                if (!addr.regex) {
                        *err = SAM_ERR_REGEX;
                        return NULL;
                }
                break;
        case '$': /* end of file */
        case '.':
        case '+':
        case '-':
        case '%':
                (*s)++;
                break;
        default:
                return NULL;
        }

        if ((addr.right = address_parse_simple(vis, s, err))) {
                switch (addr.right->type) {
                case '.':
                case '$':
                        return NULL;
                case '#':
                case 'l':
                case '/':
                case '?':
                        if (addr.type != '+' && addr.type != '-') {
                                Address *plus = address_new();
                                if (!plus) {
                                        address_free(addr.right);
                                        return NULL;
                                }
                                plus->type = '+';
                                plus->right = addr.right;
                                addr.right = plus;
                        }
                        break;
                }
        }

        Address *ret = address_new();
        if (!ret) {
                address_free(addr.right);
                return NULL;
        }
        *ret = addr;
        return ret;
}

static Address *address_parse_compound(Vis *vis, const char **s, enum SamError *err) {
        Address addr = { 0 }, *left = address_parse_simple(vis, s, err), *right = NULL;
        skip_spaces(s);
        addr.type = **s;
        switch (addr.type) {
        case ',': /* a1,a2 */
        case ';': /* a1;a2 */
                (*s)++;
                right = address_parse_compound(vis, s, err);
                if (right && (right->type == ',' || right->type == ';') && !right->left) {
                        *err = SAM_ERR_ADDRESS;
                        goto fail;
                }
                break;
        default:
                return left;
        }

        addr.left = left;
        addr.right = right;

        Address *ret = address_new();
        if (ret) {
                *ret = addr;
                return ret;
        }

fail:
        address_free(left);
        address_free(right);
        return NULL;
}

static Command *command_new(const char *name) {
        Command *cmd = calloc(1, sizeof(Command));
        if (!cmd)
                return NULL;
        if (name && !(cmd->argv[0] = strdup(name))) {
                free(cmd);
                return NULL;
        }
        return cmd;
}

static void command_free(Command *cmd) {
        if (!cmd)
                return;

        for (Command *c = cmd->cmd, *next; c; c = next) {
                next = c->next;
                command_free(c);
        }

        for (const char **args = cmd->argv; *args; args++)
                free((void*)*args);
        address_free(cmd->address);
        text_regex_free(cmd->regex);
        free(cmd);
}

static const CommandDef *command_lookup(Vis *vis, const char *name) {
        return map_closest(vis->cmds, name);
}

static Command *command_parse(Vis *vis, const char **s, enum SamError *err) {
        if (!**s) {
                *err = SAM_ERR_COMMAND;
                return NULL;
        }
        Command *cmd = command_new(NULL);
        if (!cmd)
                return NULL;

        cmd->address = address_parse_compound(vis, s, err);
        skip_spaces(s);

        cmd->argv[0] = parse_cmdname(s);

        if (!cmd->argv[0]) {
                char name[2] = { **s ? **s : 'p', '\0' };
                if (**s)
                        (*s)++;
                if (!(cmd->argv[0] = strdup(name)))
                        goto fail;
        }

        const CommandDef *cmddef = command_lookup(vis, cmd->argv[0]);
        if (!cmddef) {
                *err = SAM_ERR_COMMAND;
                goto fail;
        }

        cmd->cmddef = cmddef;

        if (strcmp(cmd->argv[0], "{") == 0) {
                Command *prev = NULL, *next;
                int level = vis->nesting_level++;
                do {
                        while (**s == ' ' || **s == '\t' || **s == '\n')
                                (*s)++;
                        next = command_parse(vis, s, err);
                        if (*err)
                                goto fail;
                        if (prev)
                                prev->next = next;
                        else
                                cmd->cmd = next;
                } while ((prev = next));
                if (level != vis->nesting_level) {
                        *err = SAM_ERR_UNMATCHED_BRACE;
                        goto fail;
                }
        } else if (strcmp(cmd->argv[0], "}") == 0) {
                if (vis->nesting_level-- == 0) {
                        *err = SAM_ERR_UNMATCHED_BRACE;
                        goto fail;
                }
                command_free(cmd);
                return NULL;
        }

        if (cmddef->flags & CMD_ADDRESS_NONE && cmd->address) {
                *err = SAM_ERR_NO_ADDRESS;
                goto fail;
        }

        if (cmddef->flags & CMD_FORCE && **s == '!') {
                cmd->flags = '!';
                (*s)++;
        }

        if ((cmddef->flags & CMD_COUNT) && (*err = parse_count(s, &cmd->count)))
                goto fail;

        if (cmddef->flags & CMD_REGEX) {
                if ((cmddef->flags & CMD_REGEX_DEFAULT) && (!**s || **s == ' ')) {
                        skip_spaces(s);
                } else {
                        const char *before = *s;
                        cmd->regex = parse_regex(vis, s);
                        if (!cmd->regex && (*s != before || !(cmddef->flags & CMD_COUNT))) {
                                *err = SAM_ERR_REGEX;
                                goto fail;
                        }
                }
        }

        if (cmddef->flags & CMD_SHELL && !(cmd->argv[1] = parse_shellcmd(vis, s))) {
                *err = SAM_ERR_SHELL;
                goto fail;
        }

        if (cmddef->flags & CMD_TEXT && !(cmd->argv[1] = parse_text(s, &cmd->count))) {
                *err = SAM_ERR_TEXT;
                goto fail;
        }

        if (cmddef->flags & CMD_ARGV) {
                parse_argv(s, &cmd->argv[1], MAX_ARGV-2);
                cmd->argv[MAX_ARGV-1] = NULL;
        }

        if (cmddef->flags & CMD_CMD) {
                skip_spaces(s);
                if (cmddef->defcmd && (**s == '\n' || **s == '}' || **s == '\0')) {
                        if (**s == '\n')
                                (*s)++;
                        if (!(cmd->cmd = command_new(cmddef->defcmd)))
                                goto fail;
                        cmd->cmd->cmddef = command_lookup(vis, cmddef->defcmd);
                } else {
                        if (!(cmd->cmd = command_parse(vis, s, err)))
                                goto fail;
                        if (strcmp(cmd->argv[0], "X") == 0 || strcmp(cmd->argv[0], "Y") == 0) {
                                Command *sel = command_new("select");
                                if (!sel)
                                        goto fail;
                                sel->cmd = cmd->cmd;
                                sel->cmddef = &cmddef_select;
                                cmd->cmd = sel;
                        }
                }
        }

        return cmd;
fail:
        command_free(cmd);
        return NULL;
}

static Command *sam_parse(Vis *vis, const char *cmd, enum SamError *err) {
        vis->nesting_level = 0;
        const char **s = &cmd;
        Command *c = command_parse(vis, s, err);
        if (!c)
                return NULL;
        while (**s == ' ' || **s == '\t' || **s == '\n')
                (*s)++;
        if (**s) {
                *err = SAM_ERR_NEWLINE;
                command_free(c);
                return NULL;
        }

        Command *sel = command_new("select");
        if (!sel) {
                command_free(c);
                return NULL;
        }
        sel->cmd = c;
        sel->cmddef = &cmddef_select;
        return sel;
}

static Filerange address_line_evaluate(Address *addr, File *file, Filerange *range, int sign) {
        Text *txt = file->text;
        size_t offset = addr->number != EPOS ? addr->number : 1;
        size_t start = range->start, end = range->end, line;
        if (sign > 0) {
                char c;
                if (start < end && end > 0 && text_byte_get(txt, end-1, &c) && c == '\n')
                        end--;
                line = text_lineno_by_pos(txt, end);
                line = text_pos_by_lineno(txt, line + offset);
        } else if (sign < 0) {
                line = text_lineno_by_pos(txt, start);
                line = offset < line ? text_pos_by_lineno(txt, line - offset) : 0;
        } else {
                if (addr->number == 0)
                        return text_range_new(0, 0);
                line = text_pos_by_lineno(txt, addr->number);
        }

        if (addr->type == 'g')
                return text_range_new(line, line);
        else
                return text_range_new(line, text_line_next(txt, line));
}

static Filerange address_evaluate(Address *addr, File *file, Selection *sel, Filerange *range, int sign) {
        Filerange ret = text_range_empty();

        do {
                switch (addr->type) {
                case '#':
                        if (sign > 0)
                                ret.start = ret.end = range->end + addr->number;
                        else if (sign < 0)
                                ret.start = ret.end = range->start - addr->number;
                        else
                                ret = text_range_new(addr->number, addr->number);
                        break;
                case 'l':
                case 'g':
                        ret = address_line_evaluate(addr, file, range, sign);
                        break;
                case '\'':
                {
                        size_t pos = EPOS;
                        Array *marks = &file->marks[addr->number];
                        size_t idx = sel ? view_selections_number(sel) : 0;
                        SelectionRegion *sr = array_get(marks, idx);
                        if (sr)
                                pos = text_mark_get(file->text, sr->cursor);
                        ret = text_range_new(pos, pos);
                        break;
                }
                case '?':
                        sign = sign == 0 ? -1 : -sign;
                        /* fall through */
                case '/':
                        if (sign >= 0)
                                ret = text_object_search_forward(file->text, range->end, addr->regex);
                        else
                                ret = text_object_search_backward(file->text, range->start, addr->regex);
                        break;
                case '$':
                {
                        size_t size = text_size(file->text);
                        ret = text_range_new(size, size);
                        break;
                }
                case '.':
                        ret = *range;
                        break;
                case '+':
                case '-':
                        sign = addr->type == '+' ? +1 : -1;
                        if (!addr->right || addr->right->type == '+' || addr->right->type == '-')
                                ret = address_line_evaluate(addr, file, range, sign);
                        break;
                case ',':
                case ';':
                {
                        Filerange left, right;
                        if (addr->left)
                                left = address_evaluate(addr->left, file, sel, range, 0);
                        else
                                left = text_range_new(0, 0);

                        if (addr->type == ';')
                                range = &left;

                        if (addr->right) {
                                right = address_evaluate(addr->right, file, sel, range, 0);
                        } else {
                                size_t size = text_size(file->text);
                                right = text_range_new(size, size);
                        }
                        /* TODO: enforce strict ordering? */
                        return text_range_union(&left, &right);
                }
                case '%':
                        return text_range_new(0, text_size(file->text));
                }
                if (text_range_valid(&ret))
                        range = &ret;
        } while ((addr = addr->right));

        return ret;
}

static bool count_evaluate(Command *cmd) {
        Count *count = &cmd->count;
        if (count->mod)
                return count->start ? cmd->iteration % count->start == 0 : true;
        return count->start <= cmd->iteration && cmd->iteration <= count->end;
}

static bool sam_execute(Vis *vis, Win *win, Command *cmd, Selection *sel, Filerange *range) {
        bool ret = true;
        if (cmd->address && win)
                *range = address_evaluate(cmd->address, win->file, sel, range, 0);

        cmd->iteration++;
        switch (cmd->argv[0][0]) {
        case '{':
        {
                for (Command *c = cmd->cmd; c && ret; c = c->next)
                        ret &= sam_execute(vis, win, c, NULL, range);
                view_selections_dispose_force(sel);
                break;
        }
        default:
                ret = cmd->cmddef->func(vis, win, cmd, cmd->argv, sel, range);
                break;
        }
        return ret;
}

static enum SamError validate(Command *cmd, bool loop, bool group) {
        if (cmd->cmddef->flags & CMD_DESTRUCTIVE) {
                if (loop)
                        return SAM_ERR_LOOP_INVALID_CMD;
                if (group)
                        return SAM_ERR_GROUP_INVALID_CMD;
        }

        group |= (cmd->cmddef->flags & CMD_GROUP);
        loop  |= (cmd->cmddef->flags & CMD_LOOP);
        for (Command *c = cmd->cmd; c; c = c->next) {
                enum SamError err = validate(c, loop, group);
                if (err != SAM_ERR_OK)
                        return err;
        }
        return SAM_ERR_OK;
}

static enum SamError command_validate(Command *cmd) {
        return validate(cmd, false, false);
}

static bool count_negative(Command *cmd) {
        if (cmd->count.start < 0 || cmd->count.end < 0)
                return true;
        for (Command *c = cmd->cmd; c; c = c->next) {
                if (c->cmddef->func != cmd_extract && c->cmddef->func != cmd_select) {
                        if (count_negative(c))
                                return true;
                }
        }
        return false;
}

static void count_init(Command *cmd, int max) {
        Count *count = &cmd->count;
        cmd->iteration = 0;
        if (count->start < 0)
                count->start += max;
        if (count->end < 0)
                count->end += max;
        for (Command *c = cmd->cmd; c; c = c->next) {
                if (c->cmddef->func != cmd_extract && c->cmddef->func != cmd_select)
                        count_init(c, max);
        }
}

enum SamError sam_cmd(Vis *vis, const char *s) {
        enum SamError err = SAM_ERR_OK;
        if (!s)
                return err;

        Command *cmd = sam_parse(vis, s, &err);
        if (!cmd) {
                if (err == SAM_ERR_OK)
                        err = SAM_ERR_MEMORY;
                return err;
        }

        err = command_validate(cmd);
        if (err != SAM_ERR_OK) {
                command_free(cmd);
                return err;
        }

        for (File *file = vis->files; file; file = file->next) {
                if (file->internal)
                        continue;
                sam_transcript_init(&file->transcript);
        }

        bool visual = vis->mode->visual;
        size_t primary_pos = vis->win ? view_cursor_get(vis->win->view) : EPOS;
        Filerange range = text_range_empty();
        sam_execute(vis, vis->win, cmd, NULL, &range);

        for (File *file = vis->files; file; file = file->next) {
                if (file->internal)
                        continue;
                Transcript *t = &file->transcript;
                if (t->error != SAM_ERR_OK) {
                        err = t->error;
                        sam_transcript_free(t);
                        continue;
                }
                vis_file_snapshot(vis, file);
                ptrdiff_t delta = 0;
                for (Change *c = t->changes; c; c = c->next) {
                        c->range.start += delta;
                        c->range.end += delta;
                        if (c->type & TRANSCRIPT_DELETE) {
                                text_delete_range(file->text, &c->range);
                                delta -= text_range_size(&c->range);
                                if (c->sel && c->type == TRANSCRIPT_DELETE) {
                                        if (visual)
                                                view_selections_dispose_force(c->sel);
                                        else
                                                view_cursors_to(c->sel, c->range.start);
                                }
                        }
                        if (c->type & TRANSCRIPT_INSERT) {
                                for (int i = 0; i < c->count; i++) {
                                        text_insert(file->text, c->range.start, c->data, c->len);
                                        delta += c->len;
                                }
                                Filerange r = text_range_new(c->range.start,
                                                             c->range.start + c->len * c->count);
                                if (c->sel) {
                                        if (visual) {
                                                view_selections_set(c->sel, &r);
                                                view_selections_anchor(c->sel, true);
                                        } else {
                                                if (memchr(c->data, '\n', c->len))
                                                        view_cursors_to(c->sel, r.start);
                                                else
                                                        view_cursors_to(c->sel, r.end);
                                        }
                                } else if (visual) {
                                        Selection *sel = view_selections_new(c->win->view, r.start);
                                        if (sel) {
                                                view_selections_set(sel, &r);
                                                view_selections_anchor(sel, true);
                                        }
                                }
                        }
                }
                sam_transcript_free(&file->transcript);
                vis_file_snapshot(vis, file);
        }

        for (Win *win = vis->windows; win; win = win->next)
                view_selections_normalize(win->view);

        if (vis->win) {
                if (primary_pos != EPOS && view_selection_disposed(vis->win->view))
                        view_cursor_to(vis->win->view, primary_pos);
                view_selections_primary_set(view_selections(vis->win->view));
                vis_jumplist_save(vis);
                bool completed = true;
                for (Selection *s = view_selections(vis->win->view); s; s = view_selections_next(s)) {
                        if (view_selections_anchored(s)) {
                                completed = false;
                                break;
                        }
                }
                vis_mode_switch(vis, completed ? VIS_MODE_NORMAL : VIS_MODE_VISUAL);
        }
        command_free(cmd);
        return err;
}

/* process text input, substitute register content for backreferences etc. */
Buffer text(Vis *vis, const char *text) {
        Buffer buf;
        buffer_init(&buf);
        for (size_t len = strcspn(text, "\\&"); *text; len = strcspn(++text, "\\&")) {
                buffer_append(&buf, text, len);
                text += len;
                enum VisRegister regid = VIS_REG_INVALID;
                switch (text[0]) {
                case '&':
                        regid = VIS_REG_AMPERSAND;
                        break;
                case '\\':
                        if ('1' <= text[1] && text[1] <= '9') {
                                regid = VIS_REG_1 + text[1] - '1';
                                text++;
                        } else if (text[1] == '\\' || text[1] == '&') {
                                text++;
                        }
                        break;
                case '\0':
                        goto out;
                }

                const char *data;
                size_t reglen = 0;
                if (regid != VIS_REG_INVALID) {
                        data = register_get(vis, &vis->registers[regid], &reglen);
                } else {
                        data = text;
                        reglen = 1;
                }
                buffer_append(&buf, data, reglen);
        }
out:
        return buf;
}

static bool cmd_insert(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        Buffer buf = text(vis, argv[1]);
        size_t len = buffer_length(&buf);
        char *data = buffer_move(&buf);
        bool ret = sam_insert(win, sel, range->start, data, len, cmd->count.start);
        if (!ret)
                free(data);
        return ret;
}

static bool cmd_append(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        Buffer buf = text(vis, argv[1]);
        size_t len = buffer_length(&buf);
        char *data = buffer_move(&buf);
        bool ret = sam_insert(win, sel, range->end, data, len, cmd->count.start);
        if (!ret)
                free(data);
        return ret;
}

static bool cmd_change(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        Buffer buf = text(vis, argv[1]);
        size_t len = buffer_length(&buf);
        char *data = buffer_move(&buf);
        bool ret = sam_change(win, sel, range, data, len, cmd->count.start);
        if (!ret)
                free(data);
        return ret;
}

static bool cmd_delete(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        return win && sam_delete(win, sel, range);
}

static bool cmd_guard(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        bool match = false;
        RegexMatch captures[1];
        size_t len = text_range_size(range);
        if (!cmd->regex)
                match = true;
        else if (!text_search_range_forward(win->file->text, range->start, len, cmd->regex, 1, captures, 0))
                match = captures[0].start < range->end;
        if ((count_evaluate(cmd) && match) ^ (argv[0][0] == 'v'))
                return sam_execute(vis, win, cmd->cmd, sel, range);
        view_selections_dispose_force(sel);
        return true;
}

static int extract(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range, bool simulate) {
        bool ret = true;
        int count = 0;
        Text *txt = win->file->text;

        if (cmd->regex) {
                bool trailing_match = false;
                size_t start = range->start, end = range->end, last_start = EPOS;
                size_t nsub = 1 + text_regex_nsub(cmd->regex);
                if (nsub > 10)
                        nsub = 10;
                RegexMatch match[nsub];
                while (start < end || trailing_match) {
                        trailing_match = false;
                        char c;
                        int flags = start > range->start &&
                                    text_byte_get(txt, start - 1, &c) && c != '\n' ?
                                    REG_NOTBOL : 0;
                        bool found = !text_search_range_forward(txt, start, end - start,
                                                                cmd->regex, nsub, match,
                                                                flags);
                        Filerange r = text_range_empty();
                        if (found) {
                                if (argv[0][0] == 'x')
                                        r = text_range_new(match[0].start, match[0].end);
                                else
                                        r = text_range_new(start, match[0].start);
                                if (match[0].start == match[0].end) {
                                        if (last_start == match[0].start) {
                                                start++;
                                                continue;
                                        }
                                        /* in Plan 9's regexp library ^ matches the beginning
                                         * of a line, however in POSIX with REG_NEWLINE ^
                                         * matches the zero-length string immediately after a
                                         * newline. Try filtering out the last such match at EOF.
                                         */
                                        if (end == match[0].start && start > range->start)
                                                break;
                                }
                                start = match[0].end;
                                if (start == end)
                                        trailing_match = true;
                        } else {
                                if (argv[0][0] == 'y')
                                        r = text_range_new(start, end);
                                start = end;
                        }

                        if (text_range_valid(&r)) {
                                if (found) {
                                        for (size_t i = 0; i < nsub; i++) {
                                                Register *reg = &vis->registers[VIS_REG_AMPERSAND+i];
                                                register_put_range(vis, reg, txt, &match[i]);
                                        }
                                }
                                if (simulate)
                                        count++;
                                else
                                        ret &= sam_execute(vis, win, cmd->cmd, NULL, &r);
                                last_start = start;
                        }
                }
        } else {
                size_t start = range->start, end = range->end;
                while (start < end) {
                        size_t next = text_line_next(txt, start);
                        if (next > end)
                                next = end;
                        Filerange r = text_range_new(start, next);
                        if (start == next || !text_range_valid(&r))
                                break;
                        if (simulate)
                                count++;
                        else
                                ret &= sam_execute(vis, win, cmd->cmd, NULL, &r);
                        start = next;
                }
        }

        if (!simulate)
                view_selections_dispose_force(sel);
        return simulate ? count : ret;
}

static bool cmd_extract(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        int matches = 0;
        if (count_negative(cmd->cmd))
                matches = extract(vis, win, cmd, argv, sel, range, true);
        count_init(cmd->cmd, matches+1);
        return extract(vis, win, cmd, argv, sel, range, false);
}

static bool cmd_select(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        Filerange r = text_range_empty();
        if (!win)
                return sam_execute(vis, NULL, cmd->cmd, NULL, &r);
        bool ret = true;
        View *view = win->view;
        Text *txt = win->file->text;
        bool multiple_cursors = view_selections_count(view) > 1;
        Selection *primary = view_selections_primary_get(view);

        if (vis->mode->visual)
                count_init(cmd->cmd, view_selections_count(view)+1);

        for (Selection *s = view_selections(view), *next; s && ret; s = next) {
                next = view_selections_next(s);
                size_t pos = view_cursors_pos(s);
                if (vis->mode->visual) {
                        r = view_selections_get(s);
                } else if (cmd->cmd->address) {
                        /* convert a single line range to a goto line motion */
                        if (!multiple_cursors && cmd->cmd->cmddef->func == cmd_print) {
                                Address *addr = cmd->cmd->address;
                                switch (addr->type) {
                                case '+':
                                case '-':
                                        addr = addr->right;
                                        /* fall through */
                                case 'l':
                                        if (addr && addr->type == 'l' && !addr->right)
                                                addr->type = 'g';
                                        break;
                                }
                        }
                        r = text_range_new(pos, pos);
                } else if (cmd->cmd->cmddef->flags & CMD_ADDRESS_POS) {
                        r = text_range_new(pos, pos);
                } else if (cmd->cmd->cmddef->flags & CMD_ADDRESS_LINE) {
                        r = text_object_line(txt, pos);
                } else if (cmd->cmd->cmddef->flags & CMD_ADDRESS_AFTER) {
                        size_t next_line = text_line_next(txt, pos);
                        r = text_range_new(next_line, next_line);
                } else if (cmd->cmd->cmddef->flags & CMD_ADDRESS_ALL) {
                        r = text_range_new(0, text_size(txt));
                } else if (!multiple_cursors && (cmd->cmd->cmddef->flags & CMD_ADDRESS_ALL_1CURSOR)) {
                        r = text_range_new(0, text_size(txt));
                } else {
                        r = text_range_new(pos, text_char_next(txt, pos));
                }
                if (!text_range_valid(&r))
                        r = text_range_new(0, 0);
                ret &= sam_execute(vis, win, cmd->cmd, s, &r);
                if (cmd->cmd->cmddef->flags & CMD_ONCE)
                        break;
        }

        if (vis->win && vis->win->view == view && primary != view_selections_primary_get(view))
                view_selections_primary_set(view_selections(view));
        return ret;
}

static bool cmd_print(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win || !text_range_valid(range))
                return false;
        View *view = win->view;
        if (!sel)
                sel = view_selections_new_force(view, range->start);
        if (!sel)
                return false;
        if (range->start != range->end) {
                view_selections_set(sel, range);
                view_selections_anchor(sel, true);
        } else {
                view_cursors_to(sel, range->start);
                view_selection_clear(sel);
        }
        return true;
}

static bool cmd_files(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        bool ret = true;
        for (Win *win = vis->windows; win; win = win->next) {
                if (win->file->internal)
                        continue;
                bool match = !cmd->regex || (win->file->name &&
                             text_regex_match(cmd->regex, win->file->name, 0));
                if (match ^ (argv[0][0] == 'Y')) {
                        Filerange def = text_range_new(0, 0);
                        ret &= sam_execute(vis, win, cmd->cmd, NULL, &def);
                }
        }
        return ret;
}

static bool cmd_substitute(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        vis_info_show(vis, "Use :x/pattern/ c/replacement/ instead");
        return false;
}

/* cmd_write stores win->file's contents end emits pre/post events.
 * If the range r covers the whole file, it is updated to account for
 * potential file's text mutation by a FILE_SAVE_PRE callback.
 */
static bool cmd_write(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *r) {
        if (!win)
                return false;

        File *file = win->file;
        if (sam_transcript_error(&file->transcript, SAM_ERR_WRITE_CONFLICT))
                return false;

        Text *text = file->text;
        Filerange range_all = text_range_new(0, text_size(text));
        bool write_entire_file = text_range_equal(r, &range_all);

        const char *filename = argv[1];
        if (!filename)
                filename = file->name;
        if (!filename) {
                if (file->fd == -1) {
                        vis_info_show(vis, "Filename expected");
                        return false;
                }
                if (!strchr(argv[0], 'q')) {
                        vis_info_show(vis, "No filename given, use 'wq' to write to stdout");
                        return false;
                }

                if (!vis_event_emit(vis, VIS_EVENT_FILE_SAVE_PRE, file, (char*)NULL) && cmd->flags != '!') {
                        vis_info_show(vis, "Rejected write to stdout by pre-save hook");
                        return false;
                }
                /* a pre-save hook may have changed the text; need to re-take the range */
                if (write_entire_file)
                        *r = text_range_new(0, text_size(text));

                bool visual = vis->mode->visual;

                for (Selection *s = view_selections(win->view); s; s = view_selections_next(s)) {
                        Filerange range = visual ? view_selections_get(s) : *r;
                        ssize_t written = text_write_range(text, &range, file->fd);
                        if (written == -1 || (size_t)written != text_range_size(&range)) {
                                vis_info_show(vis, "Can not write to stdout");
                                return false;
                        }
                        if (!visual)
                                break;
                }

                /* make sure the file is marked as saved i.e. not modified */
                text_save(text, NULL);
                vis_event_emit(vis, VIS_EVENT_FILE_SAVE_POST, file, (char*)NULL);
                return true;
        }

        if (!argv[1] && cmd->flags != '!') {
                if (vis->mode->visual) {
                        vis_info_show(vis, "WARNING: file will be reduced to active selection");
                        return false;
                }
                if (!write_entire_file) {
                        vis_info_show(vis, "WARNING: file will be reduced to provided range");
                        return false;
                }
        }

        for (const char **name = argv[1] ? &argv[1] : (const char*[]){ filename, NULL }; *name; name++) {

                char *path = absolute_path(*name);
                if (!path)
                        return false;

                struct stat meta;
                bool existing_file = !stat(path, &meta);
                bool same_file = existing_file && file->name &&
                                 file->stat.st_dev == meta.st_dev && file->stat.st_ino == meta.st_ino;

                if (cmd->flags != '!') {
                        if (same_file && file->stat.st_mtime && file->stat.st_mtime < meta.st_mtime) {
                                vis_info_show(vis, "WARNING: file has been changed since reading it");
                                goto err;
                        }
                        if (existing_file && !same_file) {
                                vis_info_show(vis, "WARNING: file exists");
                                goto err;
                        }
                }

                if (!vis_event_emit(vis, VIS_EVENT_FILE_SAVE_PRE, file, path) && cmd->flags != '!') {
                        vis_info_show(vis, "Rejected write to `%s' by pre-save hook", path);
                        goto err;
                }
                /* a pre-save hook may have changed the text; need to re-take the range */
                if (write_entire_file)
                        *r = text_range_new(0, text_size(text));

                TextSave *ctx = text_save_begin(text, path, file->save_method);
                if (!ctx) {
                        const char *msg = errno ? strerror(errno) : "try changing `:set savemethod`";
                        vis_info_show(vis, "Can't write `%s': %s", path, msg);
                        goto err;
                }

                bool failure = false;
                bool visual = vis->mode->visual;

                for (Selection *s = view_selections(win->view); s; s = view_selections_next(s)) {
                        Filerange range = visual ? view_selections_get(s) : *r;
                        ssize_t written = text_save_write_range(ctx, &range);
                        failure = (written == -1 || (size_t)written != text_range_size(&range));
                        if (failure) {
                                text_save_cancel(ctx);
                                break;
                        }

                        if (!visual)
                                break;
                }

                if (failure || !text_save_commit(ctx)) {
                        vis_info_show(vis, "Can't write `%s': %s", path, strerror(errno));
                        goto err;
                }

                if (!file->name) {
                        file_name_set(file, path);
                        same_file = true;
                }
                if (same_file)
                        file->stat = text_stat(text);
                vis_event_emit(vis, VIS_EVENT_FILE_SAVE_POST, file, path);
                free(path);
                continue;

        err:
                free(path);
                return false;
        }
        return true;
}

static ssize_t read_buffer(void *context, char *data, size_t len) {
        buffer_append(context, data, len);
        return len;
}

static bool cmd_filter(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;

        Buffer bufout, buferr;
        buffer_init(&bufout);
        buffer_init(&buferr);

        int status = vis_pipe(vis, win->file, range, &argv[1], &bufout, read_buffer, &buferr, read_buffer);

        if (vis->interrupted) {
                vis_info_show(vis, "Command cancelled");
        } else if (status == 0) {
                size_t len = buffer_length(&bufout);
                char *data = buffer_move(&bufout);
                if (!sam_change(win, sel, range, data, len, 1))
                        free(data);
        } else {
                vis_info_show(vis, "Command failed %s", buffer_content0(&buferr));
        }

        buffer_release(&bufout);
        buffer_release(&buferr);

        return !vis->interrupted && status == 0;
}

static bool cmd_launch(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        Filerange invalid = text_range_new(sel ? view_cursors_pos(sel) : range->start, EPOS);
        return cmd_filter(vis, win, cmd, argv, sel, &invalid);
}

static bool cmd_pipein(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        Filerange filter_range = text_range_new(range->end, range->end);
        bool ret = cmd_filter(vis, win, cmd, argv, sel, &filter_range);
        if (ret)
                ret = sam_delete(win, NULL, range);
        return ret;
}

static bool cmd_pipeout(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        if (!win)
                return false;
        Buffer buferr;
        buffer_init(&buferr);

        int status = vis_pipe(vis, win->file, range, (const char*[]){ argv[1], NULL }, NULL, NULL, &buferr, read_buffer);

        if (vis->interrupted)
                vis_info_show(vis, "Command cancelled");
        else if (status != 0)
                vis_info_show(vis, "Command failed %s", buffer_content0(&buferr));

        buffer_release(&buferr);

        return !vis->interrupted && status == 0;
}

static bool cmd_cd(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
        const char *dir = argv[1];
        if (!dir)
                dir = getenv("HOME");
        return dir && chdir(dir) == 0;
}

#include "vis-cmds.c"