[llvm-rc] Add basic RC scripts parsing ability.

As for now, the parser supports a limited set of statements and
resources. This will be extended in the following patches.

Thanks to Nico Weber (thakis) for his original work in this area.

Differential Revision: https://reviews.llvm.org/D36340

llvm-svn: 311175

1 files changed, 265 insertions, 0 deletions

diff --git a/llvm/tools/llvm-rc/ResourceScriptParser.cpp b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
new file mode 100644
index 00000000000..f284551cddc
--- /dev/null
+++ b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
@@ -0,0 +1,265 @@
+//===-- ResourceScriptParser.cpp --------------------------------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+//
+// This implements the parser defined in ResourceScriptParser.h.
+//
+//===---------------------------------------------------------------------===//
+
+#include "ResourceScriptParser.h"
+
+// Take an expression returning llvm::Error and forward the error if it exists.
+#define RETURN_IF_ERROR(Expr)                                                  \
+  if (auto Err = (Expr))                                                       \
+    return std::move(Err);
+
+// Take an expression returning llvm::Expected<T> and assign it to Var or
+// forward the error out of the function.
+#define ASSIGN_OR_RETURN(Var, Expr)                                            \
+  auto Var = (Expr);                                                           \
+  if (!Var)                                                                    \
+    return Var.takeError();
+
+namespace llvm {
+namespace rc {
+
+RCParser::ParserError::ParserError(const Twine Expected, const LocIter CurLoc,
+                                   const LocIter End)
+    : ErrorLoc(CurLoc), FileEnd(End) {
+  CurMessage = "Error parsing file: expected " + Expected.str() + ", got " +
+               (CurLoc == End ? "<EOF>" : CurLoc->value()).str();
+}
+
+char RCParser::ParserError::ID = 0;
+
+RCParser::RCParser(const std::vector<RCToken> &TokenList)
+    : Tokens(TokenList), CurLoc(Tokens.begin()), End(Tokens.end()) {}
+
+RCParser::RCParser(std::vector<RCToken> &&TokenList)
+    : Tokens(std::move(TokenList)), CurLoc(Tokens.begin()), End(Tokens.end()) {}
+
+bool RCParser::isEof() const { return CurLoc == End; }
+
+RCParser::ParseType RCParser::parseSingleResource() {
+  // The first thing we read is usually a resource's name. However, in some
+  // cases (LANGUAGE and STRINGTABLE) the resources don't have their names
+  // and the first token to be read is the type.
+  ASSIGN_OR_RETURN(NameToken, readTypeOrName());
+
+  if (NameToken->equalsLower("LANGUAGE"))
+    return parseLanguageResource();
+  else if (NameToken->equalsLower("STRINGTABLE"))
+    return parseStringTableResource();
+
+  // If it's not an unnamed resource, what we've just read is a name. Now,
+  // read resource type;
+  ASSIGN_OR_RETURN(TypeToken, readTypeOrName());
+
+  ParseType Result = std::unique_ptr<RCResource>();
+  (void)!Result;
+
+  if (TypeToken->equalsLower("ICON"))
+    Result = parseIconResource();
+  else
+    return getExpectedError("resource type", /* IsAlreadyRead = */ true);
+
+  if (Result)
+    (*Result)->setName(*NameToken);
+
+  return Result;
+}
+
+bool RCParser::isNextTokenKind(Kind TokenKind) const {
+  return !isEof() && look().kind() == TokenKind;
+}
+
+const RCToken &RCParser::look() const {
+  assert(!isEof());
+  return *CurLoc;
+}
+
+const RCToken &RCParser::read() {
+  assert(!isEof());
+  return *CurLoc++;
+}
+
+void RCParser::consume() {
+  assert(!isEof());
+  CurLoc++;
+}
+
+Expected<uint32_t> RCParser::readInt() {
+  if (!isNextTokenKind(Kind::Int))
+    return getExpectedError("integer");
+  return read().intValue();
+}
+
+Expected<StringRef> RCParser::readString() {
+  if (!isNextTokenKind(Kind::String))
+    return getExpectedError("string");
+  return read().value();
+}
+
+Expected<StringRef> RCParser::readIdentifier() {
+  if (!isNextTokenKind(Kind::Identifier))
+    return getExpectedError("identifier");
+  return read().value();
+}
+
+Expected<IntOrString> RCParser::readTypeOrName() {
+  // We suggest that the correct resource name or type should be either an
+  // identifier or an integer. The original RC tool is much more liberal.
+  if (!isNextTokenKind(Kind::Identifier) && !isNextTokenKind(Kind::Int))
+    return getExpectedError("int or identifier");
+
+  const RCToken &Tok = read();
+  if (Tok.kind() == Kind::Int)
+    return IntOrString(Tok.intValue());
+  else
+    return IntOrString(Tok.value());
+}
+
+Error RCParser::consumeType(Kind TokenKind) {
+  if (isNextTokenKind(TokenKind)) {
+    consume();
+    return Error::success();
+  }
+
+  switch (TokenKind) {
+#define TOKEN(TokenName)                                                       \
+  case Kind::TokenName:                                                        \
+    return getExpectedError(#TokenName);
+#define SHORT_TOKEN(TokenName, TokenCh)                                        \
+  case Kind::TokenName:                                                        \
+    return getExpectedError(#TokenCh);
+#include "ResourceScriptTokenList.h"
+#undef SHORT_TOKEN
+#undef TOKEN
+  }
+}
+
+bool RCParser::consumeOptionalType(Kind TokenKind) {
+  if (isNextTokenKind(TokenKind)) {
+    consume();
+    return true;
+  }
+
+  return false;
+}
+
+Expected<SmallVector<uint32_t, 8>>
+RCParser::readIntsWithCommas(size_t MinCount, size_t MaxCount) {
+  assert(MinCount <= MaxCount);
+
+  SmallVector<uint32_t, 8> Result;
+
+  auto FailureHandler =
+      [&](llvm::Error Err) -> Expected<SmallVector<uint32_t, 8>> {
+    if (Result.size() < MinCount)
+      return std::move(Err);
+    consumeError(std::move(Err));
+    return Result;
+  };
+
+  for (size_t i = 0; i < MaxCount; ++i) {
+    // Try to read a comma unless we read the first token.
+    // Sometimes RC tool requires them and sometimes not. We decide to
+    // always require them.
+    if (i >= 1) {
+      if (auto CommaError = consumeType(Kind::Comma))
+        return FailureHandler(std::move(CommaError));
+    }
+
+    if (auto IntResult = readInt())
+      Result.push_back(*IntResult);
+    else
+      return FailureHandler(IntResult.takeError());
+  }
+
+  return Result;
+}
+
+// As for now, we ignore the extended set of statements.
+Expected<OptionalStmtList> RCParser::parseOptionalStatements(bool IsExtended) {
+  OptionalStmtList Result;
+
+  // The last statement is always followed by the start of the block.
+  while (!isNextTokenKind(Kind::BlockBegin)) {
+    ASSIGN_OR_RETURN(SingleParse, parseSingleOptionalStatement(IsExtended));
+    Result.addStmt(std::move(*SingleParse));
+  }
+
+  return Result;
+}
+
+Expected<std::unique_ptr<OptionalStmt>>
+RCParser::parseSingleOptionalStatement(bool) {
+  ASSIGN_OR_RETURN(TypeToken, readIdentifier());
+  if (TypeToken->equals_lower("CHARACTERISTICS"))
+    return parseCharacteristicsStmt();
+  else if (TypeToken->equals_lower("LANGUAGE"))
+    return parseLanguageStmt();
+  else if (TypeToken->equals_lower("VERSION"))
+    return parseVersionStmt();
+  else
+    return getExpectedError("optional statement type, BEGIN or '{'",
+                            /* IsAlreadyRead = */ true);
+}
+
+RCParser::ParseType RCParser::parseLanguageResource() {
+  // Read LANGUAGE as an optional statement. If it's read correctly, we can
+  // upcast it to RCResource.
+  return parseLanguageStmt();
+}
+
+RCParser::ParseType RCParser::parseIconResource() {
+  ASSIGN_OR_RETURN(Arg, readString());
+  return make_unique<IconResource>(*Arg);
+}
+
+RCParser::ParseType RCParser::parseStringTableResource() {
+  ASSIGN_OR_RETURN(OptStatements, parseOptionalStatements());
+  RETURN_IF_ERROR(consumeType(Kind::BlockBegin));
+
+  auto Table = make_unique<StringTableResource>(std::move(*OptStatements));
+
+  // Read strings until we reach the end of the block.
+  while (!consumeOptionalType(Kind::BlockEnd)) {
+    // Each definition consists of string's ID (an integer) and a string.
+    // Some examples in documentation suggest that there might be a comma in
+    // between, however we strictly adhere to the single statement definition.
+    ASSIGN_OR_RETURN(IDResult, readInt());
+    ASSIGN_OR_RETURN(StrResult, readString());
+    Table->addString(*IDResult, *StrResult);
+  }
+
+  return Table;
+}
+
+RCParser::ParseOptionType RCParser::parseLanguageStmt() {
+  ASSIGN_OR_RETURN(Args, readIntsWithCommas(/* min = */ 2, /* max = */ 2));
+  return make_unique<LanguageResource>((*Args)[0], (*Args)[1]);
+}
+
+RCParser::ParseOptionType RCParser::parseCharacteristicsStmt() {
+  ASSIGN_OR_RETURN(Arg, readInt());
+  return make_unique<CharacteristicsStmt>(*Arg);
+}
+
+RCParser::ParseOptionType RCParser::parseVersionStmt() {
+  ASSIGN_OR_RETURN(Arg, readInt());
+  return make_unique<VersionStmt>(*Arg);
+}
+
+Error RCParser::getExpectedError(const Twine Message, bool IsAlreadyRead) {
+  return make_error<ParserError>(
+      Message, IsAlreadyRead ? std::prev(CurLoc) : CurLoc, End);
+}
+
+} // namespace rc
+} // namespace llvm