include/llvm/LineEditor/LineEditor.h

   1 //===-- llvm/LineEditor/LineEditor.h - line editor --------------*- C++ -*-===//
   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 #ifndef LLVM_LINEEDITOR_LINEEDITOR_H
  10 #define LLVM_LINEEDITOR_LINEEDITOR_H
  11
  12 #include "llvm/ADT/Optional.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include <cstdio>
  15 #include <memory>
  16 #include <string>
  17 #include <utility>
  18 #include <vector>
  19
  20 namespace llvm {
  21
  22 class LineEditor {
  23 public:
  24   /// Create a LineEditor object.
  25   ///
  26   /// \param ProgName The name of the current program. Used to form a default
  27   /// prompt.
  28   /// \param HistoryPath Path to the file in which to store history data, if
  29   /// possible.
  30   /// \param In The input stream used by the editor.
  31   /// \param Out The output stream used by the editor.
  32   /// \param Err The error stream used by the editor.
  33   LineEditor(StringRef ProgName, StringRef HistoryPath = "", FILE *In = stdin,
  34              FILE *Out = stdout, FILE *Err = stderr);
  35   ~LineEditor();
  36
  37   /// Reads a line.
  38   ///
  39   /// \return The line, or llvm::Optional<std::string>() on EOF.
  40   llvm::Optional<std::string> readLine() const;
  41
  42   void saveHistory();
  43   void loadHistory();
  44
  45   static std::string getDefaultHistoryPath(StringRef ProgName);
  46
  47   /// The action to perform upon a completion request.
  48   struct CompletionAction {
  49     enum ActionKind {
  50       /// Insert Text at the cursor position.
  51       AK_Insert,
  52       /// Show Completions, or beep if the list is empty.
  53       AK_ShowCompletions
  54     };
  55
  56     ActionKind Kind;
  57
  58     /// The text to insert.
  59     std::string Text;
  60
  61     /// The list of completions to show.
  62     std::vector<std::string> Completions;
  63   };
  64
  65   /// A possible completion at a given cursor position.
  66   struct Completion {
  67     Completion() {}
  68     Completion(const std::string &TypedText, const std::string &DisplayText)
  69         : TypedText(TypedText), DisplayText(DisplayText) {}
  70
  71     /// The text to insert. If the user has already input some of the
  72     /// completion, this should only include the rest of the text.
  73     std::string TypedText;
  74
  75     /// A description of this completion. This may be the completion itself, or
  76     /// maybe a summary of its type or arguments.
  77     std::string DisplayText;
  78   };
  79
  80   /// Set the completer for this LineEditor. A completer is a function object
  81   /// which takes arguments of type StringRef (the string to complete) and
  82   /// size_t (the zero-based cursor position in the StringRef) and returns a
  83   /// CompletionAction.
  84   template <typename T> void setCompleter(T Comp) {
  85     Completer.reset(new CompleterModel<T>(Comp));
  86   }
  87
  88   /// Set the completer for this LineEditor to the given list completer.
  89   /// A list completer is a function object which takes arguments of type
  90   /// StringRef (the string to complete) and size_t (the zero-based cursor
  91   /// position in the StringRef) and returns a std::vector<Completion>.
  92   template <typename T> void setListCompleter(T Comp) {
  93     Completer.reset(new ListCompleterModel<T>(Comp));
  94   }
  95
  96   /// Use the current completer to produce a CompletionAction for the given
  97   /// completion request. If the current completer is a list completer, this
  98   /// will return an AK_Insert CompletionAction if each completion has a common
  99   /// prefix, or an AK_ShowCompletions CompletionAction otherwise.
 100   ///
 101   /// \param Buffer The string to complete
 102   /// \param Pos The zero-based cursor position in the StringRef
 103   CompletionAction getCompletionAction(StringRef Buffer, size_t Pos) const;
 104
 105   const std::string &getPrompt() const { return Prompt; }
 106   void setPrompt(const std::string &P) { Prompt = P; }
 107
 108   // Public so callbacks in LineEditor.cpp can use it.
 109   struct InternalData;
 110
 111 private:
 112   std::string Prompt;
 113   std::string HistoryPath;
 114   std::unique_ptr<InternalData> Data;
 115
 116   struct CompleterConcept {
 117     virtual ~CompleterConcept();
 118     virtual CompletionAction complete(StringRef Buffer, size_t Pos) const = 0;
 119   };
 120
 121   struct ListCompleterConcept : CompleterConcept {
 122     ~ListCompleterConcept() override;
 123     CompletionAction complete(StringRef Buffer, size_t Pos) const override;
 124     static std::string getCommonPrefix(const std::vector<Completion> &Comps);
 125     virtual std::vector<Completion> getCompletions(StringRef Buffer,
 126                                                    size_t Pos) const = 0;
 127   };
 128
 129   template <typename T>
 130   struct CompleterModel : CompleterConcept {
 131     CompleterModel(T Value) : Value(Value) {}
 132     CompletionAction complete(StringRef Buffer, size_t Pos) const override {
 133       return Value(Buffer, Pos);
 134     }
 135     T Value;
 136   };
 137
 138   template <typename T>
 139   struct ListCompleterModel : ListCompleterConcept {
 140     ListCompleterModel(T Value) : Value(std::move(Value)) {}
 141     std::vector<Completion> getCompletions(StringRef Buffer,
 142                                            size_t Pos) const override {
 143       return Value(Buffer, Pos);
 144     }
 145     T Value;
 146   };
 147
 148   std::unique_ptr<const CompleterConcept> Completer;
 149 };
 150
 151 }
 152
 153 #endif