llvm/utils/TableGen/GlobalISel/CodeExpander.cpp

   1 //===- CodeExpander.cpp - Expand variables in a string --------------------===//
   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 /// \file Expand the variables in a string.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "CodeExpander.h"
  14 #include "CodeExpansions.h"
  15 #include "llvm/Support/raw_ostream.h"
  16 #include "llvm/TableGen/Error.h"
  17
  18 using namespace llvm;
  19
  20 void CodeExpander::emit(raw_ostream &OS) const {
  21   StringRef Current = Code;
  22
  23   while (!Current.empty()) {
  24     size_t Pos = Current.find_first_of("$\n\\");
  25     if (Pos == StringRef::npos) {
  26       OS << Current;
  27       Current = "";
  28       continue;
  29     }
  30
  31     OS << Current.substr(0, Pos);
  32     Current = Current.substr(Pos);
  33
  34     if (Current.startswith("\n")) {
  35       OS << "\n" << Indent;
  36       Current = Current.drop_front(1);
  37       continue;
  38     }
  39
  40     if (Current.startswith("\\$") || Current.startswith("\\\\")) {
  41       OS << Current[1];
  42       Current = Current.drop_front(2);
  43       continue;
  44     }
  45
  46     if (Current.startswith("\\")) {
  47       Current = Current.drop_front(1);
  48       continue;
  49     }
  50
  51     if (Current.startswith("${")) {
  52       StringRef StartVar = Current;
  53       Current = Current.drop_front(2);
  54       StringRef Var;
  55       std::tie(Var, Current) = Current.split("}");
  56
  57       // Warn if we split because no terminator was found.
  58       StringRef EndVar = StartVar.drop_front(2 /* ${ */ + Var.size());
  59       if (EndVar.empty()) {
  60         PrintWarning(Loc, "Unterminated expansion '${" + Var + "'");
  61         PrintNote("Code: [{" + Code + "}]");
  62       }
  63
  64       auto ValueI = Expansions.find(Var);
  65       if (ValueI == Expansions.end()) {
  66         PrintError(Loc,
  67                    "Attempt to expand an undeclared variable '" + Var + "'");
  68         PrintNote("Code: [{" + Code + "}]");
  69       }
  70       if (ShowExpansions)
  71         OS << "/*$" << Var << "{*/";
  72       OS << Expansions.lookup(Var);
  73       if (ShowExpansions)
  74         OS << "/*}*/";
  75       continue;
  76     }
  77
  78     PrintWarning(Loc, "Assuming missing escape character: \\$");
  79     PrintNote("Code: [{" + Code + "}]");
  80     OS << "$";
  81     Current = Current.drop_front(1);
  82   }
  83 }