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// Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef FORTRAN_PARSER_PRESCAN_H_
#define FORTRAN_PARSER_PRESCAN_H_
// Defines a fast Fortran source prescanning phase that implements some
// character-level features of the language that can be inefficient to
// support directly in a backtracking parser. This phase handles Fortran
// line continuation, comment removal, card image margins, padding out
// fixed form character literals on truncated card images, file
// inclusion, and driving the Fortran source preprocessor.
#include "characters.h"
#include "features.h"
#include "message.h"
#include "provenance.h"
#include "token-sequence.h"
#include <bitset>
#include <optional>
#include <string>
#include <unordered_set>
namespace Fortran::parser {
class Messages;
class Preprocessor;
class Prescanner {
public:
Prescanner(
Messages &, CookedSource &, Preprocessor &, LanguageFeatureControl);
Prescanner(const Prescanner &);
Messages &messages() const { return messages_; }
Prescanner &set_fixedForm(bool yes) {
inFixedForm_ = yes;
return *this;
}
Prescanner &set_encoding(Encoding code) {
encoding_ = code;
return *this;
}
Prescanner &set_fixedFormColumnLimit(int limit) {
fixedFormColumnLimit_ = limit;
return *this;
}
Prescanner &AddCompilerDirectiveSentinel(const std::string &);
void Prescan(ProvenanceRange);
void Statement();
void NextLine();
// Callbacks for use by Preprocessor.
bool IsAtEnd() const { return lineStart_ >= limit_; }
bool IsNextLinePreprocessorDirective() const;
TokenSequence TokenizePreprocessorDirective();
Provenance GetCurrentProvenance() const { return GetProvenance(at_); }
void Say(Message &&);
void Say(MessageFixedText, ProvenanceRange);
void Say(MessageFormattedText &&, ProvenanceRange);
private:
struct LineClassification {
enum class Kind {
Comment,
ConditionalCompilationDirective,
PreprocessorDirective,
Include,
CompilerDirective,
Source
};
LineClassification(Kind k, std::size_t po = 0, const char *s = nullptr)
: kind{k}, payloadOffset{po}, sentinel{s} {}
LineClassification(LineClassification &&) = default;
Kind kind;
std::size_t payloadOffset; // byte offset of content
const char *sentinel; // if it's a compiler directive
};
void BeginSourceLine(const char *at) {
at_ = at;
column_ = 1;
tabInCurrentLine_ = false;
slashInCurrentLine_ = false;
preventHollerith_ = false;
delimiterNesting_ = 0;
}
void BeginSourceLineAndAdvance() {
BeginSourceLine(lineStart_);
NextLine();
}
Provenance GetProvenance(const char *sourceChar) const {
return startProvenance_ + (sourceChar - start_);
}
ProvenanceRange GetProvenanceRange(
const char *first, const char *afterLast) const {
std::size_t bytes = afterLast - first;
return {startProvenance_ + (first - start_), bytes};
}
void EmitChar(TokenSequence &tokens, char ch) {
tokens.PutNextTokenChar(ch, GetCurrentProvenance());
}
void EmitInsertedChar(TokenSequence &tokens, char ch) {
Provenance provenance{cooked_.allSources().CompilerInsertionProvenance(ch)};
tokens.PutNextTokenChar(ch, provenance);
}
char EmitCharAndAdvance(TokenSequence &tokens, char ch) {
EmitChar(tokens, ch);
NextChar();
return *at_;
}
bool InCompilerDirective() const { return directiveSentinel_ != nullptr; }
bool InFixedFormSource() const {
return inFixedForm_ && !inPreprocessorDirective_ && !InCompilerDirective();
}
void LabelField(TokenSequence &);
void SkipToEndOfLine();
void NextChar();
void SkipSpaces();
bool NextToken(TokenSequence &);
bool ExponentAndKind(TokenSequence &);
void QuotedCharacterLiteral(TokenSequence &);
void Hollerith(TokenSequence &, int);
bool PadOutCharacterLiteral(TokenSequence &);
bool SkipCommentLine();
bool IsFixedFormCommentLine(const char *) const;
bool IsFreeFormComment(const char *) const;
std::optional<std::size_t> IsIncludeLine(const char *) const;
void FortranInclude(const char *quote);
const char *IsPreprocessorDirectiveLine(const char *) const;
const char *FixedFormContinuationLine(bool mightNeedSpace);
const char *FreeFormContinuationLine(bool ampersand);
bool FixedFormContinuation(bool mightNeedSpace);
bool FreeFormContinuation();
std::optional<LineClassification> IsFixedFormCompilerDirectiveLine(
const char *) const;
std::optional<LineClassification> IsFreeFormCompilerDirectiveLine(
const char *) const;
const char *IsCompilerDirectiveSentinel(const char *) const;
LineClassification ClassifyLine(const char *) const;
void SourceFormChange(std::string &&);
Messages &messages_;
CookedSource &cooked_;
Preprocessor &preprocessor_;
LanguageFeatureControl features_;
bool inFixedForm_{false};
int fixedFormColumnLimit_{72};
Encoding encoding_{Encoding::UTF8};
int delimiterNesting_{0};
int prescannerNesting_{0};
Provenance startProvenance_;
const char *start_{nullptr}; // beginning of current source file content
const char *limit_{nullptr}; // first address after end of current source
const char *lineStart_{nullptr}; // next line to process; <= limit_
const char *directiveSentinel_{nullptr}; // current compiler directive
// This data members are state for processing the source line containing
// "at_", which goes to up to the newline character before "lineStart_".
const char *at_{nullptr}; // next character to process; < lineStart_
int column_{1}; // card image column position of next character
bool tabInCurrentLine_{false};
bool slashInCurrentLine_{false};
bool preventHollerith_{false};
bool inCharLiteral_{false};
bool inPreprocessorDirective_{false};
// In some edge cases of compiler directive continuation lines, it
// is necessary to treat the line break as a space character by
// setting this flag, which is cleared by EmitChar().
bool insertASpace_{false};
const Provenance spaceProvenance_{
cooked_.allSources().CompilerInsertionProvenance(' ')};
const Provenance backslashProvenance_{
cooked_.allSources().CompilerInsertionProvenance('\\')};
const ProvenanceRange sixSpaceProvenance_{
cooked_.allSources().AddCompilerInsertion(" "s)};
// To avoid probing the set of active compiler directive sentinel strings
// on every comment line, they're checked first with a cheap Bloom filter.
static const int prime1{1019}, prime2{1021};
std::bitset<prime2> compilerDirectiveBloomFilter_; // 128 bytes
std::unordered_set<std::string> compilerDirectiveSentinels_;
};
} // namespace Fortran::parser
#endif // FORTRAN_PARSER_PRESCAN_H_
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