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llvm-project/llvm/lib/TableGen/TGLexer.cpp

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//===- TGLexer.cpp - Lexer for TableGen -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implement the Lexer for TableGen.
//
//===----------------------------------------------------------------------===//
#include "TGLexer.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Config/config.h" // for strtoull()/strtoll() define
#include "llvm/Support/Compiler.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/TableGen/Error.h"
#include <algorithm>
#include <cctype>
#include <cerrno>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace llvm;
namespace {
// A list of supported preprocessing directives with their
// internal token kinds and names.
struct {
tgtok::TokKind Kind;
const char *Word;
} PreprocessorDirs[] = {
{ tgtok::Ifdef, "ifdef" },
{ tgtok::Else, "else" },
{ tgtok::Endif, "endif" },
{ tgtok::Define, "define" }
};
} // end anonymous namespace
TGLexer::TGLexer(SourceMgr &SM, ArrayRef<std::string> Macros) : SrcMgr(SM) {
CurBuffer = SrcMgr.getMainFileID();
CurBuf = SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer();
CurPtr = CurBuf.begin();
TokStart = nullptr;
// Pretend that we enter the "top-level" include file.
PrepIncludeStack.push_back(
make_unique<std::vector<PreprocessorControlDesc>>());
// Put all macros defined in the command line into the DefinedMacros set.
std::for_each(Macros.begin(), Macros.end(),
[this](const std::string &MacroName) {
DefinedMacros.insert(MacroName);
});
}
SMLoc TGLexer::getLoc() const {
return SMLoc::getFromPointer(TokStart);
}
/// ReturnError - Set the error to the specified string at the specified
/// location. This is defined to always return tgtok::Error.
tgtok::TokKind TGLexer::ReturnError(SMLoc Loc, const Twine &Msg) {
PrintError(Loc, Msg);
return tgtok::Error;
}
tgtok::TokKind TGLexer::ReturnError(const char *Loc, const Twine &Msg) {
return ReturnError(SMLoc::getFromPointer(Loc), Msg);
}
bool TGLexer::processEOF() {
SMLoc ParentIncludeLoc = SrcMgr.getParentIncludeLoc(CurBuffer);
if (ParentIncludeLoc != SMLoc()) {
// If prepExitInclude() detects a problem with the preprocessing
// control stack, it will return false. Pretend that we reached
// the final EOF and stop lexing more tokens by returning false
// to LexToken().
if (!prepExitInclude(false))
return false;
CurBuffer = SrcMgr.FindBufferContainingLoc(ParentIncludeLoc);
CurBuf = SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer();
CurPtr = ParentIncludeLoc.getPointer();
// Make sure TokStart points into the parent file's buffer.
// LexToken() assigns to it before calling getNextChar(),
// so it is pointing into the included file now.
TokStart = CurPtr;
return true;
}
// Pretend that we exit the "top-level" include file.
// Note that in case of an error (e.g. control stack imbalance)
// the routine will issue a fatal error.
prepExitInclude(true);
return false;
}
int TGLexer::getNextChar() {
char CurChar = *CurPtr++;
switch (CurChar) {
default:
return (unsigned char)CurChar;
case 0: {
// A nul character in the stream is either the end of the current buffer or
// a random nul in the file. Disambiguate that here.
if (CurPtr-1 != CurBuf.end())
return 0; // Just whitespace.
// Otherwise, return end of file.
--CurPtr; // Another call to lex will return EOF again.
return EOF;
}
case '\n':
case '\r':
// Handle the newline character by ignoring it and incrementing the line
// count. However, be careful about 'dos style' files with \n\r in them.
// Only treat a \n\r or \r\n as a single line.
if ((*CurPtr == '\n' || (*CurPtr == '\r')) &&
*CurPtr != CurChar)
++CurPtr; // Eat the two char newline sequence.
return '\n';
}
}
int TGLexer::peekNextChar(int Index) const {
return *(CurPtr + Index);
}
tgtok::TokKind TGLexer::LexToken(bool FileOrLineStart) {
TokStart = CurPtr;
// This always consumes at least one character.
int CurChar = getNextChar();
switch (CurChar) {
default:
// Handle letters: [a-zA-Z_]
if (isalpha(CurChar) || CurChar == '_')
return LexIdentifier();
// Unknown character, emit an error.
return ReturnError(TokStart, "Unexpected character");
case EOF:
// Lex next token, if we just left an include file.
// Note that leaving an include file means that the next
// symbol is located at the end of 'include "..."'
// construct, so LexToken() is called with default
// false parameter.
if (processEOF())
return LexToken();
// Return EOF denoting the end of lexing.
return tgtok::Eof;
case ':': return tgtok::colon;
case ';': return tgtok::semi;
case '.': return tgtok::period;
case ',': return tgtok::comma;
case '<': return tgtok::less;
case '>': return tgtok::greater;
case ']': return tgtok::r_square;
case '{': return tgtok::l_brace;
case '}': return tgtok::r_brace;
case '(': return tgtok::l_paren;
case ')': return tgtok::r_paren;
case '=': return tgtok::equal;
case '?': return tgtok::question;
case '#':
if (FileOrLineStart) {
tgtok::TokKind Kind = prepIsDirective();
if (Kind != tgtok::Error)
return lexPreprocessor(Kind);
}
return tgtok::paste;
case '\r':
PrintFatalError("getNextChar() must never return '\r'");
return tgtok::Error;
case 0:
case ' ':
case '\t':
// Ignore whitespace.
return LexToken(FileOrLineStart);
case '\n':
// Ignore whitespace, and identify the new line.
return LexToken(true);
case '/':
// If this is the start of a // comment, skip until the end of the line or
// the end of the buffer.
if (*CurPtr == '/')
SkipBCPLComment();
else if (*CurPtr == '*') {
if (SkipCComment())
return tgtok::Error;
} else // Otherwise, this is an error.
return ReturnError(TokStart, "Unexpected character");
return LexToken(FileOrLineStart);
case '-': case '+':
case '0': case '1': case '2': case '3': case '4': case '5': case '6':
case '7': case '8': case '9': {
int NextChar = 0;
if (isdigit(CurChar)) {
// Allow identifiers to start with a number if it is followed by
// an identifier. This can happen with paste operations like
// foo#8i.
int i = 0;
do {
NextChar = peekNextChar(i++);
} while (isdigit(NextChar));
if (NextChar == 'x' || NextChar == 'b') {
// If this is [0-9]b[01] or [0-9]x[0-9A-fa-f] this is most
// likely a number.
int NextNextChar = peekNextChar(i);
switch (NextNextChar) {
default:
break;
case '0': case '1':
if (NextChar == 'b')
return LexNumber();
LLVM_FALLTHROUGH;
case '2': case '3': case '4': case '5':
case '6': case '7': case '8': case '9':
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
if (NextChar == 'x')
return LexNumber();
break;
}
}
}
if (isalpha(NextChar) || NextChar == '_')
return LexIdentifier();
return LexNumber();
}
case '"': return LexString();
case '$': return LexVarName();
case '[': return LexBracket();
case '!': return LexExclaim();
}
}
/// LexString - Lex "[^"]*"
tgtok::TokKind TGLexer::LexString() {
const char *StrStart = CurPtr;
CurStrVal = "";
while (*CurPtr != '"') {
// If we hit the end of the buffer, report an error.
if (*CurPtr == 0 && CurPtr == CurBuf.end())
return ReturnError(StrStart, "End of file in string literal");
if (*CurPtr == '\n' || *CurPtr == '\r')
return ReturnError(StrStart, "End of line in string literal");
if (*CurPtr != '\\') {
CurStrVal += *CurPtr++;
continue;
}
++CurPtr;
switch (*CurPtr) {
case '\\': case '\'': case '"':
// These turn into their literal character.
CurStrVal += *CurPtr++;
break;
case 't':
CurStrVal += '\t';
++CurPtr;
break;
case 'n':
CurStrVal += '\n';
++CurPtr;
break;
case '\n':
case '\r':
return ReturnError(CurPtr, "escaped newlines not supported in tblgen");
// If we hit the end of the buffer, report an error.
case '\0':
if (CurPtr == CurBuf.end())
return ReturnError(StrStart, "End of file in string literal");
LLVM_FALLTHROUGH;
default:
return ReturnError(CurPtr, "invalid escape in string literal");
}
}
++CurPtr;
return tgtok::StrVal;
}
tgtok::TokKind TGLexer::LexVarName() {
if (!isalpha(CurPtr[0]) && CurPtr[0] != '_')
return ReturnError(TokStart, "Invalid variable name");
// Otherwise, we're ok, consume the rest of the characters.
const char *VarNameStart = CurPtr++;
while (isalpha(*CurPtr) || isdigit(*CurPtr) || *CurPtr == '_')
++CurPtr;
CurStrVal.assign(VarNameStart, CurPtr);
return tgtok::VarName;
}
tgtok::TokKind TGLexer::LexIdentifier() {
// The first letter is [a-zA-Z_].
const char *IdentStart = TokStart;
// Match the rest of the identifier regex: [0-9a-zA-Z_]*
while (isalpha(*CurPtr) || isdigit(*CurPtr) || *CurPtr == '_')
++CurPtr;
// Check to see if this identifier is a keyword.
StringRef Str(IdentStart, CurPtr-IdentStart);
if (Str == "include") {
if (LexInclude()) return tgtok::Error;
return Lex();
}
tgtok::TokKind Kind = StringSwitch<tgtok::TokKind>(Str)
.Case("int", tgtok::Int)
.Case("bit", tgtok::Bit)
.Case("bits", tgtok::Bits)
.Case("string", tgtok::String)
.Case("list", tgtok::List)
.Case("code", tgtok::Code)
.Case("dag", tgtok::Dag)
.Case("class", tgtok::Class)
.Case("def", tgtok::Def)
.Case("foreach", tgtok::Foreach)
.Case("defm", tgtok::Defm)
.Case("defset", tgtok::Defset)
.Case("multiclass", tgtok::MultiClass)
.Case("field", tgtok::Field)
.Case("let", tgtok::Let)
.Case("in", tgtok::In)
.Default(tgtok::Id);
if (Kind == tgtok::Id)
CurStrVal.assign(Str.begin(), Str.end());
return Kind;
}
/// LexInclude - We just read the "include" token. Get the string token that
/// comes next and enter the include.
bool TGLexer::LexInclude() {
// The token after the include must be a string.
tgtok::TokKind Tok = LexToken();
if (Tok == tgtok::Error) return true;
if (Tok != tgtok::StrVal) {
PrintError(getLoc(), "Expected filename after include");
return true;
}
// Get the string.
std::string Filename = CurStrVal;
std::string IncludedFile;
CurBuffer = SrcMgr.AddIncludeFile(Filename, SMLoc::getFromPointer(CurPtr),
IncludedFile);
if (!CurBuffer) {
PrintError(getLoc(), "Could not find include file '" + Filename + "'");
return true;
}
DependenciesMapTy::const_iterator Found = Dependencies.find(IncludedFile);
if (Found != Dependencies.end()) {
PrintError(getLoc(),
"File '" + IncludedFile + "' has already been included.");
SrcMgr.PrintMessage(Found->second, SourceMgr::DK_Note,
"previously included here");
return true;
}
Dependencies.insert(std::make_pair(IncludedFile, getLoc()));
// Save the line number and lex buffer of the includer.
CurBuf = SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer();
CurPtr = CurBuf.begin();
PrepIncludeStack.push_back(
make_unique<std::vector<PreprocessorControlDesc>>());
return false;
}
void TGLexer::SkipBCPLComment() {
++CurPtr; // skip the second slash.
while (true) {
switch (*CurPtr) {
case '\n':
case '\r':
return; // Newline is end of comment.
case 0:
// If this is the end of the buffer, end the comment.
if (CurPtr == CurBuf.end())
return;
break;
}
// Otherwise, skip the character.
++CurPtr;
}
}
/// SkipCComment - This skips C-style /**/ comments. The only difference from C
/// is that we allow nesting.
bool TGLexer::SkipCComment() {
++CurPtr; // skip the star.
unsigned CommentDepth = 1;
while (true) {
int CurChar = getNextChar();
switch (CurChar) {
case EOF:
PrintError(TokStart, "Unterminated comment!");
return true;
case '*':
// End of the comment?
if (CurPtr[0] != '/') break;
++CurPtr; // End the */.
if (--CommentDepth == 0)
return false;
break;
case '/':
// Start of a nested comment?
if (CurPtr[0] != '*') break;
++CurPtr;
++CommentDepth;
break;
}
}
}
/// LexNumber - Lex:
/// [-+]?[0-9]+
/// 0x[0-9a-fA-F]+
/// 0b[01]+
tgtok::TokKind TGLexer::LexNumber() {
if (CurPtr[-1] == '0') {
if (CurPtr[0] == 'x') {
++CurPtr;
const char *NumStart = CurPtr;
while (isxdigit(CurPtr[0]))
++CurPtr;
// Requires at least one hex digit.
if (CurPtr == NumStart)
return ReturnError(TokStart, "Invalid hexadecimal number");
errno = 0;
CurIntVal = strtoll(NumStart, nullptr, 16);
if (errno == EINVAL)
return ReturnError(TokStart, "Invalid hexadecimal number");
if (errno == ERANGE) {
errno = 0;
CurIntVal = (int64_t)strtoull(NumStart, nullptr, 16);
if (errno == EINVAL)
return ReturnError(TokStart, "Invalid hexadecimal number");
if (errno == ERANGE)
return ReturnError(TokStart, "Hexadecimal number out of range");
}
return tgtok::IntVal;
} else if (CurPtr[0] == 'b') {
++CurPtr;
const char *NumStart = CurPtr;
while (CurPtr[0] == '0' || CurPtr[0] == '1')
++CurPtr;
// Requires at least one binary digit.
if (CurPtr == NumStart)
return ReturnError(CurPtr-2, "Invalid binary number");
CurIntVal = strtoll(NumStart, nullptr, 2);
return tgtok::BinaryIntVal;
}
}
// Check for a sign without a digit.
if (!isdigit(CurPtr[0])) {
if (CurPtr[-1] == '-')
return tgtok::minus;
else if (CurPtr[-1] == '+')
return tgtok::plus;
}
while (isdigit(CurPtr[0]))
++CurPtr;
CurIntVal = strtoll(TokStart, nullptr, 10);
return tgtok::IntVal;
}
/// LexBracket - We just read '['. If this is a code block, return it,
/// otherwise return the bracket. Match: '[' and '[{ ( [^}]+ | }[^]] )* }]'
tgtok::TokKind TGLexer::LexBracket() {
if (CurPtr[0] != '{')
return tgtok::l_square;
++CurPtr;
const char *CodeStart = CurPtr;
while (true) {
int Char = getNextChar();
if (Char == EOF) break;
if (Char != '}') continue;
Char = getNextChar();
if (Char == EOF) break;
if (Char == ']') {
CurStrVal.assign(CodeStart, CurPtr-2);
return tgtok::CodeFragment;
}
}
return ReturnError(CodeStart-2, "Unterminated Code Block");
}
/// LexExclaim - Lex '!' and '![a-zA-Z]+'.
tgtok::TokKind TGLexer::LexExclaim() {
if (!isalpha(*CurPtr))
return ReturnError(CurPtr - 1, "Invalid \"!operator\"");
const char *Start = CurPtr++;
while (isalpha(*CurPtr))
++CurPtr;
// Check to see which operator this is.
tgtok::TokKind Kind =
StringSwitch<tgtok::TokKind>(StringRef(Start, CurPtr - Start))
.Case("eq", tgtok::XEq)
.Case("ne", tgtok::XNe)
.Case("le", tgtok::XLe)
.Case("lt", tgtok::XLt)
.Case("ge", tgtok::XGe)
.Case("gt", tgtok::XGt)
.Case("if", tgtok::XIf)
.Case("cond", tgtok::XCond)
.Case("isa", tgtok::XIsA)
.Case("head", tgtok::XHead)
.Case("tail", tgtok::XTail)
.Case("size", tgtok::XSize)
.Case("con", tgtok::XConcat)
.Case("dag", tgtok::XDag)
.Case("add", tgtok::XADD)
.Case("mul", tgtok::XMUL)
.Case("and", tgtok::XAND)
.Case("or", tgtok::XOR)
.Case("shl", tgtok::XSHL)
.Case("sra", tgtok::XSRA)
.Case("srl", tgtok::XSRL)
.Case("cast", tgtok::XCast)
.Case("empty", tgtok::XEmpty)
.Case("subst", tgtok::XSubst)
.Case("foldl", tgtok::XFoldl)
.Case("foreach", tgtok::XForEach)
.Case("listconcat", tgtok::XListConcat)
.Case("strconcat", tgtok::XStrConcat)
.Default(tgtok::Error);
return Kind != tgtok::Error ? Kind : ReturnError(Start-1, "Unknown operator");
}
bool TGLexer::prepExitInclude(bool IncludeStackMustBeEmpty) {
// Report an error, if preprocessor control stack for the current
// file is not empty.
if (!PrepIncludeStack.back()->empty()) {
prepReportPreprocessorStackError();
return false;
}
// Pop the preprocessing controls from the include stack.
if (PrepIncludeStack.empty()) {
PrintFatalError("Preprocessor include stack is empty");
}
PrepIncludeStack.pop_back();
if (IncludeStackMustBeEmpty) {
if (!PrepIncludeStack.empty())
PrintFatalError("Preprocessor include stack is not empty");
} else {
if (PrepIncludeStack.empty())
PrintFatalError("Preprocessor include stack is empty");
}
return true;
}
tgtok::TokKind TGLexer::prepIsDirective() const {
for (unsigned ID = 0; ID < llvm::array_lengthof(PreprocessorDirs); ++ID) {
int NextChar = *CurPtr;
bool Match = true;
unsigned I = 0;
for (; I < strlen(PreprocessorDirs[ID].Word); ++I) {
if (NextChar != PreprocessorDirs[ID].Word[I]) {
Match = false;
break;
}
NextChar = peekNextChar(I + 1);
}
// Check for whitespace after the directive. If there is no whitespace,
// then we do not recognize it as a preprocessing directive.
if (Match) {
tgtok::TokKind Kind = PreprocessorDirs[ID].Kind;
// New line and EOF may follow only #else/#endif. It will be reported
// as an error for #ifdef/#define after the call to prepLexMacroName().
if (NextChar == ' ' || NextChar == '\t' || NextChar == EOF ||
NextChar == '\n' ||
// It looks like TableGen does not support '\r' as the actual
// carriage return, e.g. getNextChar() treats a single '\r'
// as '\n'. So we do the same here.
NextChar == '\r')
return Kind;
// Allow comments after some directives, e.g.:
// #else// OR #else/**/
// #endif// OR #endif/**/
//
// Note that we do allow comments after #ifdef/#define here, e.g.
// #ifdef/**/ AND #ifdef//
// #define/**/ AND #define//
//
// These cases will be reported as incorrect after calling
// prepLexMacroName(). We could have supported C-style comments
// after #ifdef/#define, but this would complicate the code
// for little benefit.
if (NextChar == '/') {
NextChar = peekNextChar(I + 1);
if (NextChar == '*' || NextChar == '/')
return Kind;
// Pretend that we do not recognize the directive.
}
}
}
return tgtok::Error;
}
bool TGLexer::prepEatPreprocessorDirective(tgtok::TokKind Kind) {
TokStart = CurPtr;
for (unsigned ID = 0; ID < llvm::array_lengthof(PreprocessorDirs); ++ID)
if (PreprocessorDirs[ID].Kind == Kind) {
// Advance CurPtr to the end of the preprocessing word.
CurPtr += strlen(PreprocessorDirs[ID].Word);
return true;
}
PrintFatalError("Unsupported preprocessing token in "
"prepEatPreprocessorDirective()");
return false;
}
tgtok::TokKind TGLexer::lexPreprocessor(
tgtok::TokKind Kind, bool ReturnNextLiveToken) {
// We must be looking at a preprocessing directive. Eat it!
if (!prepEatPreprocessorDirective(Kind))
PrintFatalError("lexPreprocessor() called for unknown "
"preprocessor directive");
if (Kind == tgtok::Ifdef) {
StringRef MacroName = prepLexMacroName();
if (MacroName.empty())
return ReturnError(TokStart, "Expected macro name after #ifdef");
bool MacroIsDefined = DefinedMacros.count(MacroName) != 0;
// Regardless of whether we are processing tokens or not,
// we put the #ifdef control on stack.
PrepIncludeStack.back()->push_back(
{Kind, MacroIsDefined, SMLoc::getFromPointer(TokStart)});
if (!prepSkipDirectiveEnd())
return ReturnError(CurPtr,
"Only comments are supported after #ifdef NAME");
// If we were not processing tokens before this #ifdef,
// then just return back to the lines skipping code.
if (!ReturnNextLiveToken)
return Kind;
// If we were processing tokens before this #ifdef,
// and the macro is defined, then just return the next token.
if (MacroIsDefined)
return LexToken();
// We were processing tokens before this #ifdef, and the macro
// is not defined, so we have to start skipping the lines.
// If the skipping is successful, it will return the token following
// either #else or #endif corresponding to this #ifdef.
if (prepSkipRegion(ReturnNextLiveToken))
return LexToken();
return tgtok::Error;
} else if (Kind == tgtok::Else) {
// Check if this #else is correct before calling prepSkipDirectiveEnd(),
// which will move CurPtr away from the beginning of #else.
if (PrepIncludeStack.back()->empty())
return ReturnError(TokStart, "#else without #ifdef");
PreprocessorControlDesc IfdefEntry = PrepIncludeStack.back()->back();
if (IfdefEntry.Kind != tgtok::Ifdef) {
PrintError(TokStart, "double #else");
return ReturnError(IfdefEntry.SrcPos, "Previous #else is here");
}
// Replace the corresponding #ifdef's control with its negation
// on the control stack.
PrepIncludeStack.back()->pop_back();
PrepIncludeStack.back()->push_back(
{Kind, !IfdefEntry.IsDefined, SMLoc::getFromPointer(TokStart)});
if (!prepSkipDirectiveEnd())
return ReturnError(CurPtr, "Only comments are supported after #else");
// If we were processing tokens before this #else,
// we have to start skipping lines until the matching #endif.
if (ReturnNextLiveToken) {
if (prepSkipRegion(ReturnNextLiveToken))
return LexToken();
return tgtok::Error;
}
// Return to the lines skipping code.
return Kind;
} else if (Kind == tgtok::Endif) {
// Check if this #endif is correct before calling prepSkipDirectiveEnd(),
// which will move CurPtr away from the beginning of #endif.
if (PrepIncludeStack.back()->empty())
return ReturnError(TokStart, "#endif without #ifdef");
auto &IfdefOrElseEntry = PrepIncludeStack.back()->back();
if (IfdefOrElseEntry.Kind != tgtok::Ifdef &&
IfdefOrElseEntry.Kind != tgtok::Else) {
PrintFatalError("Invalid preprocessor control on the stack");
return tgtok::Error;
}
if (!prepSkipDirectiveEnd())
return ReturnError(CurPtr, "Only comments are supported after #endif");
PrepIncludeStack.back()->pop_back();
// If we were processing tokens before this #endif, then
// we should continue it.
if (ReturnNextLiveToken) {
return LexToken();
}
// Return to the lines skipping code.
return Kind;
} else if (Kind == tgtok::Define) {
StringRef MacroName = prepLexMacroName();
if (MacroName.empty())
return ReturnError(TokStart, "Expected macro name after #define");
if (!DefinedMacros.insert(MacroName).second)
PrintWarning(getLoc(),
"Duplicate definition of macro: " + Twine(MacroName));
if (!prepSkipDirectiveEnd())
return ReturnError(CurPtr,
"Only comments are supported after #define NAME");
if (!ReturnNextLiveToken) {
PrintFatalError("#define must be ignored during the lines skipping");
return tgtok::Error;
}
return LexToken();
}
PrintFatalError("Preprocessing directive is not supported");
return tgtok::Error;
}
bool TGLexer::prepSkipRegion(bool MustNeverBeFalse) {
if (!MustNeverBeFalse)
PrintFatalError("Invalid recursion.");
do {
// Skip all symbols to the line end.
prepSkipToLineEnd();
// Find the first non-whitespace symbol in the next line(s).
if (!prepSkipLineBegin())
return false;
// If the first non-blank/comment symbol on the line is '#',
// it may be a start of preprocessing directive.
//
// If it is not '#' just go to the next line.
if (*CurPtr == '#')
++CurPtr;
else
continue;
tgtok::TokKind Kind = prepIsDirective();
// If we did not find a preprocessing directive or it is #define,
// then just skip to the next line. We do not have to do anything
// for #define in the line-skipping mode.
if (Kind == tgtok::Error || Kind == tgtok::Define)
continue;
tgtok::TokKind ProcessedKind = lexPreprocessor(Kind, false);
// If lexPreprocessor() encountered an error during lexing this
// preprocessor idiom, then return false to the calling lexPreprocessor().
// This will force tgtok::Error to be returned to the tokens processing.
if (ProcessedKind == tgtok::Error)
return false;
if (Kind != ProcessedKind)
PrintFatalError("prepIsDirective() and lexPreprocessor() "
"returned different token kinds");
// If this preprocessing directive enables tokens processing,
// then return to the lexPreprocessor() and get to the next token.
// We can move from line-skipping mode to processing tokens only
// due to #else or #endif.
if (prepIsProcessingEnabled()) {
if (Kind != tgtok::Else && Kind != tgtok::Endif) {
PrintFatalError("Tokens processing was enabled by an unexpected "
"preprocessing directive");
return false;
}
return true;
}
} while (CurPtr != CurBuf.end());
// We have reached the end of the file, but never left the lines-skipping
// mode. This means there is no matching #endif.
prepReportPreprocessorStackError();
return false;
}
StringRef TGLexer::prepLexMacroName() {
// Skip whitespaces between the preprocessing directive and the macro name.
while (*CurPtr == ' ' || *CurPtr == '\t')
++CurPtr;
TokStart = CurPtr;
// Macro names start with [a-zA-Z_].
if (*CurPtr != '_' && !isalpha(*CurPtr))
return "";
// Match the rest of the identifier regex: [0-9a-zA-Z_]*
while (isalpha(*CurPtr) || isdigit(*CurPtr) || *CurPtr == '_')
++CurPtr;
return StringRef(TokStart, CurPtr - TokStart);
}
bool TGLexer::prepSkipLineBegin() {
while (CurPtr != CurBuf.end()) {
switch (*CurPtr) {
case ' ':
case '\t':
case '\n':
case '\r':
break;
case '/': {
int NextChar = peekNextChar(1);
if (NextChar == '*') {
// Skip C-style comment.
// Note that we do not care about skipping the C++-style comments.
// If the line contains "//", it may not contain any processable
// preprocessing directive. Just return CurPtr pointing to
// the first '/' in this case. We also do not care about
// incorrect symbols after the first '/' - we are in lines-skipping
// mode, so incorrect code is allowed to some extent.
// Set TokStart to the beginning of the comment to enable proper
// diagnostic printing in case of error in SkipCComment().
TokStart = CurPtr;
// CurPtr must point to '*' before call to SkipCComment().
++CurPtr;
if (SkipCComment())
return false;
} else {
// CurPtr points to the non-whitespace '/'.
return true;
}
// We must not increment CurPtr after the comment was lexed.
continue;
}
default:
return true;
}
++CurPtr;
}
// We have reached the end of the file. Return to the lines skipping
// code, and allow it to handle the EOF as needed.
return true;
}
bool TGLexer::prepSkipDirectiveEnd() {
while (CurPtr != CurBuf.end()) {
switch (*CurPtr) {
case ' ':
case '\t':
break;
case '\n':
case '\r':
return true;
case '/': {
int NextChar = peekNextChar(1);
if (NextChar == '/') {
// Skip C++-style comment.
// We may just return true now, but let's skip to the line/buffer end
// to simplify the method specification.
++CurPtr;
SkipBCPLComment();
} else if (NextChar == '*') {
// When we are skipping C-style comment at the end of a preprocessing
// directive, we can skip several lines. If any meaningful TD token
// follows the end of the C-style comment on the same line, it will
// be considered as an invalid usage of TD token.
// For example, we want to forbid usages like this one:
// #define MACRO class Class {}
// But with C-style comments we also disallow the following:
// #define MACRO /* This macro is used
// to ... */ class Class {}
// One can argue that this should be allowed, but it does not seem
// to be worth of the complication. Moreover, this matches
// the C preprocessor behavior.
// Set TokStart to the beginning of the comment to enable proper
// diagnostic printer in case of error in SkipCComment().
TokStart = CurPtr;
++CurPtr;
if (SkipCComment())
return false;
} else {
TokStart = CurPtr;
PrintError(CurPtr, "Unexpected character");
return false;
}
// We must not increment CurPtr after the comment was lexed.
continue;
}
default:
// Do not allow any non-whitespaces after the directive.
TokStart = CurPtr;
return false;
}
++CurPtr;
}
return true;
}
void TGLexer::prepSkipToLineEnd() {
while (*CurPtr != '\n' && *CurPtr != '\r' && CurPtr != CurBuf.end())
++CurPtr;
}
bool TGLexer::prepIsProcessingEnabled() {
for (auto I = PrepIncludeStack.back()->rbegin(),
E = PrepIncludeStack.back()->rend();
I != E; ++I) {
if (!I->IsDefined)
return false;
}
return true;
}
void TGLexer::prepReportPreprocessorStackError() {
if (PrepIncludeStack.back()->empty())
PrintFatalError("prepReportPreprocessorStackError() called with "
"empty control stack");
auto &PrepControl = PrepIncludeStack.back()->back();
PrintError(CurBuf.end(), "Reached EOF without matching #endif");
PrintError(PrepControl.SrcPos, "The latest preprocessor control is here");
TokStart = CurPtr;
}
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