tools/llvm-rc/ResourceScriptCppFilter.cpp

   1 //===-- ResourceScriptCppFilter.cpp ----------------------------*- 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 // This file implements an interface defined in ResourceScriptCppFilter.h.
  10 //
  11 //===---------------------------------------------------------------------===//
  12
  13 #include "ResourceScriptCppFilter.h"
  14 #include "llvm/ADT/StringExtras.h"
  15
  16 #include <vector>
  17
  18 using namespace llvm;
  19
  20 namespace {
  21
  22 class Filter {
  23 public:
  24   explicit Filter(StringRef Input) : Data(Input), DataLength(Input.size()) {}
  25
  26   std::string run();
  27
  28 private:
  29   // Parse the line, returning whether the line should be included in
  30   // the output.
  31   bool parseLine(StringRef Line);
  32
  33   bool streamEof() const;
  34
  35   StringRef Data;
  36   size_t DataLength;
  37
  38   size_t Pos = 0;
  39   bool Outputting = true;
  40 };
  41
  42 std::string Filter::run() {
  43   std::vector<StringRef> Output;
  44
  45   while (!streamEof() && Pos != StringRef::npos) {
  46     size_t LineStart = Pos;
  47     Pos = Data.find_first_of("\r\n", Pos);
  48     Pos = Data.find_first_not_of("\r\n", Pos);
  49     StringRef Line = Data.take_front(Pos).drop_front(LineStart);
  50
  51     if (parseLine(Line))
  52       Output.push_back(Line);
  53   }
  54
  55   return llvm::join(Output, "");
  56 }
  57
  58 bool Filter::parseLine(StringRef Line) {
  59   Line = Line.ltrim();
  60
  61   if (!Line.consume_front("#")) {
  62     // A normal content line, filtered according to the current mode.
  63     return Outputting;
  64   }
  65
  66   // Found a preprocessing directive line. From here on, we always return
  67   // false since the preprocessing directives should be filtered out.
  68
  69   Line.consume_front("line");
  70   if (!Line.startswith(" "))
  71     return false; // Not a line directive (pragma etc).
  72
  73   // #line 123 "path/file.h"
  74   // # 123 "path/file.h" 1
  75
  76   Line =
  77       Line.ltrim(); // There could be multiple spaces after the #line directive
  78
  79   size_t N;
  80   if (Line.consumeInteger(10, N)) // Returns true to signify an error
  81     return false;
  82
  83   Line = Line.ltrim();
  84
  85   if (!Line.consume_front("\""))
  86     return false; // Malformed line, no quote found.
  87
  88   // Split the string at the last quote (in case the path name had
  89   // escaped quotes as well).
  90   Line = Line.rsplit('"').first;
  91
  92   StringRef Ext = Line.rsplit('.').second;
  93
  94   if (Ext.equals_lower("h") || Ext.equals_lower("c")) {
  95     Outputting = false;
  96   } else {
  97     Outputting = true;
  98   }
  99
 100   return false;
 101 }
 102
 103 bool Filter::streamEof() const { return Pos == DataLength; }
 104
 105 } // anonymous namespace
 106
 107 namespace llvm {
 108
 109 std::string filterCppOutput(StringRef Input) { return Filter(Input).run(); }
 110
 111 } // namespace llvm