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