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/CommandLine.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include "llvm/TableGen/Error.h"
  18
  19 using namespace llvm;
  20
  21 void CodeExpander::emit(raw_ostream &OS) const {
  22   StringRef Current = Code;
  23
  24   while (!Current.empty()) {
  25     size_t Pos = Current.find_first_of("$\n\\");
  26     if (Pos == StringRef::npos) {
  27       OS << Current;
  28       Current = "";
  29       continue;
  30     }
  31
  32     OS << Current.substr(0, Pos);
  33     Current = Current.substr(Pos);
  34
  35     if (Current.startswith("\n")) {
  36       OS << "\n" << Indent;
  37       Current = Current.drop_front(1);
  38       continue;
  39     }
  40
  41     if (Current.startswith("\\$") || Current.startswith("\\\\")) {
  42       OS << Current[1];
  43       Current = Current.drop_front(2);
  44       continue;
  45     }
  46
  47     if (Current.startswith("\\")) {
  48       Current = Current.drop_front(1);
  49       continue;
  50     }
  51
  52     if (Current.startswith("${")) {
  53       StringRef StartVar = Current;
  54       Current = Current.drop_front(2);
  55       StringRef Var;
  56       std::tie(Var, Current) = Current.split("}");
  57
  58       // Warn if we split because no terminator was found.
  59       StringRef EndVar = StartVar.drop_front(2 /* ${ */ + Var.size());
  60       if (EndVar.empty()) {
  61         PrintWarning(Loc, "Unterminated expansion '${" + Var + "'");
  62         PrintNote("Code: [{" + Code + "}]");
  63       }
  64
  65       auto ValueI = Expansions.find(Var);
  66       if (ValueI == Expansions.end()) {
  67         PrintError(Loc,
  68                    "Attempt to expand an undeclared variable '" + Var + "'");
  69         PrintNote("Code: [{" + Code + "}]");
  70       }
  71       if (ShowExpansions)
  72         OS << "/*$" << Var << "{*/";
  73       OS << Expansions.lookup(Var);
  74       if (ShowExpansions)
  75         OS << "/*}*/";
  76       continue;
  77     }
  78
  79     PrintWarning(Loc, "Assuming missing escape character: \\$");
  80     PrintNote("Code: [{" + Code + "}]");
  81     OS << "$";
  82     Current = Current.drop_front(1);
  83   }
  84 }