llvm/lib/LineEditor/LineEditor.cpp

   1 //===-- LineEditor.cpp - line editor --------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/LineEditor/LineEditor.h"
  10 #include "llvm/ADT/SmallString.h"
  11 #include "llvm/Config/config.h"
  12 #include "llvm/Support/Path.h"
  13 #include "llvm/Support/raw_ostream.h"
  14 #include <algorithm>
  15 #include <cassert>
  16 #include <cstdio>
  17 #ifdef HAVE_LIBEDIT
  18 #include <histedit.h>
  19 #endif
  20
  21 using namespace llvm;
  22
  23 std::string LineEditor::getDefaultHistoryPath(StringRef ProgName) {
  24   SmallString<32> Path;
  25   if (sys::path::home_directory(Path)) {
  26     sys::path::append(Path, "." + ProgName + "-history");
  27     return std::string(Path.str());
  28   }
  29   return std::string();
  30 }
  31
  32 LineEditor::CompleterConcept::~CompleterConcept() = default;
  33 LineEditor::ListCompleterConcept::~ListCompleterConcept() = default;
  34
  35 std::string LineEditor::ListCompleterConcept::getCommonPrefix(
  36     const std::vector<Completion> &Comps) {
  37   assert(!Comps.empty());
  38
  39   std::string CommonPrefix = Comps[0].TypedText;
  40   for (std::vector<Completion>::const_iterator I = Comps.begin() + 1,
  41                                                E = Comps.end();
  42        I != E; ++I) {
  43     size_t Len = std::min(CommonPrefix.size(), I->TypedText.size());
  44     size_t CommonLen = 0;
  45     for (; CommonLen != Len; ++CommonLen) {
  46       if (CommonPrefix[CommonLen] != I->TypedText[CommonLen])
  47         break;
  48     }
  49     CommonPrefix.resize(CommonLen);
  50   }
  51   return CommonPrefix;
  52 }
  53
  54 LineEditor::CompletionAction
  55 LineEditor::ListCompleterConcept::complete(StringRef Buffer, size_t Pos) const {
  56   CompletionAction Action;
  57   std::vector<Completion> Comps = getCompletions(Buffer, Pos);
  58   if (Comps.empty()) {
  59     Action.Kind = CompletionAction::AK_ShowCompletions;
  60     return Action;
  61   }
  62
  63   std::string CommonPrefix = getCommonPrefix(Comps);
  64
  65   // If the common prefix is non-empty we can simply insert it. If there is a
  66   // single completion, this will insert the full completion. If there is more
  67   // than one, this might be enough information to jog the user's memory but if
  68   // not the user can also hit tab again to see the completions because the
  69   // common prefix will then be empty.
  70   if (CommonPrefix.empty()) {
  71     Action.Kind = CompletionAction::AK_ShowCompletions;
  72     for (const Completion &Comp : Comps)
  73       Action.Completions.push_back(Comp.DisplayText);
  74   } else {
  75     Action.Kind = CompletionAction::AK_Insert;
  76     Action.Text = CommonPrefix;
  77   }
  78
  79   return Action;
  80 }
  81
  82 LineEditor::CompletionAction LineEditor::getCompletionAction(StringRef Buffer,
  83                                                              size_t Pos) const {
  84   if (!Completer) {
  85     CompletionAction Action;
  86     Action.Kind = CompletionAction::AK_ShowCompletions;
  87     return Action;
  88   }
  89
  90   return Completer->complete(Buffer, Pos);
  91 }
  92
  93 #ifdef HAVE_LIBEDIT
  94
  95 // libedit-based implementation.
  96
  97 struct LineEditor::InternalData {
  98   LineEditor *LE;
  99
 100   History *Hist;
 101   EditLine *EL;
 102
 103   unsigned PrevCount;
 104   std::string ContinuationOutput;
 105
 106   FILE *Out;
 107 };
 108
 109 namespace {
 110
 111 const char *ElGetPromptFn(EditLine *EL) {
 112   LineEditor::InternalData *Data;
 113   if (el_get(EL, EL_CLIENTDATA, &Data) == 0)
 114     return Data->LE->getPrompt().c_str();
 115   return "> ";
 116 }
 117
 118 // Handles tab completion.
 119 //
 120 // This function is really horrible. But since the alternative is to get into
 121 // the line editor business, here we are.
 122 unsigned char ElCompletionFn(EditLine *EL, int ch) {
 123   LineEditor::InternalData *Data;
 124   if (el_get(EL, EL_CLIENTDATA, &Data) == 0) {
 125     if (!Data->ContinuationOutput.empty()) {
 126       // This is the continuation of the AK_ShowCompletions branch below.
 127       FILE *Out = Data->Out;
 128
 129       // Print the required output (see below).
 130       ::fwrite(Data->ContinuationOutput.c_str(),
 131                Data->ContinuationOutput.size(), 1, Out);
 132
 133       // Push a sequence of Ctrl-B characters to move the cursor back to its
 134       // original position.
 135       std::string Prevs(Data->PrevCount, '\02');
 136       ::el_push(EL, const_cast<char *>(Prevs.c_str()));
 137
 138       Data->ContinuationOutput.clear();
 139
 140       return CC_REFRESH;
 141     }
 142
 143     const LineInfo *LI = ::el_line(EL);
 144     LineEditor::CompletionAction Action = Data->LE->getCompletionAction(
 145         StringRef(LI->buffer, LI->lastchar - LI->buffer),
 146         LI->cursor - LI->buffer);
 147     switch (Action.Kind) {
 148     case LineEditor::CompletionAction::AK_Insert:
 149       ::el_insertstr(EL, Action.Text.c_str());
 150       return CC_REFRESH;
 151
 152     case LineEditor::CompletionAction::AK_ShowCompletions:
 153       if (Action.Completions.empty()) {
 154         return CC_REFRESH_BEEP;
 155       } else {
 156         // Push a Ctrl-E and a tab. The Ctrl-E causes libedit to move the cursor
 157         // to the end of the line, so that when we emit a newline we will be on
 158         // a new blank line. The tab causes libedit to call this function again
 159         // after moving the cursor. There doesn't seem to be anything we can do
 160         // from here to cause libedit to move the cursor immediately. This will
 161         // break horribly if the user has rebound their keys, so for now we do
 162         // not permit user rebinding.
 163         ::el_push(EL, const_cast<char *>("\05\t"));
 164
 165         // This assembles the output for the continuation block above.
 166         raw_string_ostream OS(Data->ContinuationOutput);
 167
 168         // Move cursor to a blank line.
 169         OS << "\n";
 170
 171         // Emit the completions.
 172         for (std::vector<std::string>::iterator I = Action.Completions.begin(),
 173                                                 E = Action.Completions.end();
 174              I != E; ++I) {
 175           OS << *I << "\n";
 176         }
 177
 178         // Fool libedit into thinking nothing has changed. Reprint its prompt
 179         // and the user input. Note that the cursor will remain at the end of
 180         // the line after this.
 181         OS << Data->LE->getPrompt()
 182            << StringRef(LI->buffer, LI->lastchar - LI->buffer);
 183
 184         // This is the number of characters we need to tell libedit to go back:
 185         // the distance between end of line and the original cursor position.
 186         Data->PrevCount = LI->lastchar - LI->cursor;
 187
 188         return CC_REFRESH;
 189       }
 190     }
 191   }
 192   return CC_ERROR;
 193 }
 194
 195 } // end anonymous namespace
 196
 197 LineEditor::LineEditor(StringRef ProgName, StringRef HistoryPath, FILE *In,
 198                        FILE *Out, FILE *Err)
 199     : Prompt((ProgName + "> ").str()), HistoryPath(std::string(HistoryPath)),
 200       Data(new InternalData) {
 201   if (HistoryPath.empty())
 202     this->HistoryPath = getDefaultHistoryPath(ProgName);
 203
 204   Data->LE = this;
 205   Data->Out = Out;
 206
 207   Data->Hist = ::history_init();
 208   assert(Data->Hist);
 209
 210   Data->EL = ::el_init(ProgName.str().c_str(), In, Out, Err);
 211   assert(Data->EL);
 212
 213   ::el_set(Data->EL, EL_PROMPT, ElGetPromptFn);
 214   ::el_set(Data->EL, EL_EDITOR, "emacs");
 215   ::el_set(Data->EL, EL_HIST, history, Data->Hist);
 216   ::el_set(Data->EL, EL_ADDFN, "tab_complete", "Tab completion function",
 217            ElCompletionFn);
 218   ::el_set(Data->EL, EL_BIND, "\t", "tab_complete", NULL);
 219   ::el_set(Data->EL, EL_BIND, "^r", "em-inc-search-prev",
 220            NULL); // Cycle through backwards search, entering string
 221   ::el_set(Data->EL, EL_BIND, "^w", "ed-delete-prev-word",
 222            NULL); // Delete previous word, behave like bash does.
 223   ::el_set(Data->EL, EL_BIND, "\033[3~", "ed-delete-next-char",
 224            NULL); // Fix the delete key.
 225   ::el_set(Data->EL, EL_CLIENTDATA, Data.get());
 226
 227   HistEvent HE;
 228   ::history(Data->Hist, &HE, H_SETSIZE, 800);
 229   ::history(Data->Hist, &HE, H_SETUNIQUE, 1);
 230   loadHistory();
 231 }
 232
 233 LineEditor::~LineEditor() {
 234   saveHistory();
 235
 236   ::history_end(Data->Hist);
 237   ::el_end(Data->EL);
 238   ::fwrite("\n", 1, 1, Data->Out);
 239 }
 240
 241 void LineEditor::saveHistory() {
 242   if (!HistoryPath.empty()) {
 243     HistEvent HE;
 244     ::history(Data->Hist, &HE, H_SAVE, HistoryPath.c_str());
 245   }
 246 }
 247
 248 void LineEditor::loadHistory() {
 249   if (!HistoryPath.empty()) {
 250     HistEvent HE;
 251     ::history(Data->Hist, &HE, H_LOAD, HistoryPath.c_str());
 252   }
 253 }
 254
 255 Optional<std::string> LineEditor::readLine() const {
 256   // Call el_gets to prompt the user and read the user's input.
 257   int LineLen = 0;
 258   const char *Line = ::el_gets(Data->EL, &LineLen);
 259
 260   // Either of these may mean end-of-file.
 261   if (!Line || LineLen == 0)
 262     return Optional<std::string>();
 263
 264   // Strip any newlines off the end of the string.
 265   while (LineLen > 0 &&
 266          (Line[LineLen - 1] == '\n' || Line[LineLen - 1] == '\r'))
 267     --LineLen;
 268
 269   HistEvent HE;
 270   if (LineLen > 0)
 271     ::history(Data->Hist, &HE, H_ENTER, Line);
 272
 273   return std::string(Line, LineLen);
 274 }
 275
 276 #else // HAVE_LIBEDIT
 277
 278 // Simple fgets-based implementation.
 279
 280 struct LineEditor::InternalData {
 281   FILE *In;
 282   FILE *Out;
 283 };
 284
 285 LineEditor::LineEditor(StringRef ProgName, StringRef HistoryPath, FILE *In,
 286                        FILE *Out, FILE *Err)
 287     : Prompt((ProgName + "> ").str()), Data(new InternalData) {
 288   Data->In = In;
 289   Data->Out = Out;
 290 }
 291
 292 LineEditor::~LineEditor() {
 293   ::fwrite("\n", 1, 1, Data->Out);
 294 }
 295
 296 void LineEditor::saveHistory() {}
 297 void LineEditor::loadHistory() {}
 298
 299 Optional<std::string> LineEditor::readLine() const {
 300   ::fprintf(Data->Out, "%s", Prompt.c_str());
 301
 302   std::string Line;
 303   do {
 304     char Buf[64];
 305     char *Res = ::fgets(Buf, sizeof(Buf), Data->In);
 306     if (!Res) {
 307       if (Line.empty())
 308         return Optional<std::string>();
 309       else
 310         return Line;
 311     }
 312     Line.append(Buf);
 313   } while (Line.empty() ||
 314            (Line[Line.size() - 1] != '\n' && Line[Line.size() - 1] != '\r'));
 315
 316   while (!Line.empty() &&
 317          (Line[Line.size() - 1] == '\n' || Line[Line.size() - 1] == '\r'))
 318     Line.resize(Line.size() - 1);
 319
 320   return Line;
 321 }
 322
 323 #endif // HAVE_LIBEDIT