1 //===--- Main.cpp - Compile BNF grammar -----------------------------------===//
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 is a tool to compile a BNF grammar, it is used by the build system to
10 // generate a necessary data bits to statically construct core pieces (Grammar,
11 // LRTable etc) of the LR parser.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang-pseudo/grammar/Grammar.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/Support/CommandLine.h"
18 #include "llvm/Support/FileSystem.h"
19 #include "llvm/Support/FormatVariadic.h"
20 #include "llvm/Support/MemoryBuffer.h"
21 #include "llvm/Support/ToolOutputFile.h"
22 #include <algorithm>
23 
24 using llvm::cl::desc;
25 using llvm::cl::init;
26 using llvm::cl::opt;
27 using llvm::cl::Required;
28 using llvm::cl::value_desc;
29 using llvm::cl::values;
30 
31 namespace {
32 enum EmitType {
33   EmitSymbolList,
34   EmitGrammarContent,
35 };
36 
37 opt<std::string> Grammar("grammar", desc("Parse a BNF grammar file."),
38                          Required);
39 opt<EmitType>
40     Emit(desc("which information to emit:"),
41          values(clEnumValN(EmitSymbolList, "emit-symbol-list",
42                            "Print nonterminal symbols (default)"),
43                 clEnumValN(EmitGrammarContent, "emit-grammar-content",
44                            "Print the BNF grammar content as a string")));
45 
46 opt<std::string> OutputFilename("o", init("-"), desc("Output"),
47                                 value_desc("file"));
48 
49 std::string readOrDie(llvm::StringRef Path) {
50   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
51       llvm::MemoryBuffer::getFile(Path);
52   if (std::error_code EC = Text.getError()) {
53     llvm::errs() << "Error: can't read grammar file '" << Path
54                  << "': " << EC.message() << "\n";
55     ::exit(1);
56   }
57   return Text.get()->getBuffer().str();
58 }
59 } // namespace
60 
61 int main(int argc, char *argv[]) {
62   llvm::cl::ParseCommandLineOptions(argc, argv, "");
63 
64   std::string GrammarText = readOrDie(Grammar);
65   std::vector<std::string> Diags;
66   auto G = clang::pseudo::Grammar::parseBNF(GrammarText, Diags);
67 
68   if (!Diags.empty()) {
69     llvm::errs() << llvm::join(Diags, "\n");
70     return 1;
71   }
72 
73   std::error_code EC;
74   llvm::ToolOutputFile Out{OutputFilename, EC, llvm::sys::fs::OF_None};
75   if (EC) {
76     llvm::errs() << EC.message() << '\n';
77     return 1;
78   }
79 
80   switch (Emit) {
81   case EmitSymbolList:
82     Out.os() << R"cpp(
83 #ifndef NONTERMINAL
84 #define NONTERMINAL(X, Y)
85 #endif
86 #ifndef RULE
87 #define RULE(X, Y)
88 #endif
89 #ifndef EXTENSION
90 #define EXTENSION(X, Y)
91 #endif
92 )cpp";
93     for (clang::pseudo::SymbolID ID = 0; ID < G.table().Nonterminals.size();
94          ++ID)
95       Out.os() << llvm::formatv("NONTERMINAL({0}, {1})\n", G.mangleSymbol(ID),
96                                 ID);
97     for (clang::pseudo::RuleID RID = 0; RID < G.table().Rules.size(); ++RID)
98       Out.os() << llvm::formatv("RULE({0}, {1})\n", G.mangleRule(RID), RID);
99     for (clang::pseudo::ExtensionID EID = 1 /*skip the sentinel 0 value*/;
100          EID < G.table().AttributeValues.size(); ++EID) {
101       llvm::StringRef Name = G.table().AttributeValues[EID];
102       assert(!Name.empty());
103       Out.os() << llvm::formatv("EXTENSION({0}, {1})\n", Name, EID);
104     }
105     Out.os() << R"cpp(
106 #undef NONTERMINAL
107 #undef RULE
108 #undef EXTENSION
109 )cpp";
110     break;
111   case EmitGrammarContent:
112     for (llvm::StringRef Line : llvm::split(GrammarText, '\n')) {
113       Out.os() << '"';
114       Out.os().write_escaped((Line + "\n").str());
115       Out.os() << "\"\n";
116     }
117     break;
118   }
119 
120   Out.keep();
121 
122   return 0;
123 }
124