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llvm-project/flang/lib/Parser/prescan.cpp

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//===-- lib/Parser/prescan.cpp --------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "prescan.h"
#include "preprocessor.h"
#include "token-sequence.h"
#include "flang/Common/idioms.h"
#include "flang/Parser/characters.h"
#include "flang/Parser/message.h"
#include "flang/Parser/source.h"
#include "llvm/Support/raw_ostream.h"
#include <cstddef>
#include <cstring>
#include <utility>
#include <vector>
namespace Fortran::parser {
using common::LanguageFeature;
static constexpr int maxPrescannerNesting{100};
Prescanner::Prescanner(Messages &messages, CookedSource &cooked,
Preprocessor &preprocessor, common::LanguageFeatureControl lfc)
: messages_{messages}, cooked_{cooked}, preprocessor_{preprocessor},
features_{lfc}, encoding_{cooked.allSources().encoding()} {}
Prescanner::Prescanner(const Prescanner &that)
: messages_{that.messages_}, cooked_{that.cooked_},
preprocessor_{that.preprocessor_}, features_{that.features_},
inFixedForm_{that.inFixedForm_},
fixedFormColumnLimit_{that.fixedFormColumnLimit_},
encoding_{that.encoding_}, prescannerNesting_{that.prescannerNesting_ +
1},
skipLeadingAmpersand_{that.skipLeadingAmpersand_},
compilerDirectiveBloomFilter_{that.compilerDirectiveBloomFilter_},
compilerDirectiveSentinels_{that.compilerDirectiveSentinels_} {}
static inline constexpr bool IsFixedFormCommentChar(char ch) {
return ch == '!' || ch == '*' || ch == 'C' || ch == 'c';
}
static void NormalizeCompilerDirectiveCommentMarker(TokenSequence &dir) {
char *p{dir.GetMutableCharData()};
char *limit{p + dir.SizeInChars()};
for (; p < limit; ++p) {
if (*p != ' ') {
CHECK(IsFixedFormCommentChar(*p));
*p = '!';
return;
}
}
DIE("compiler directive all blank");
}
void Prescanner::Prescan(ProvenanceRange range) {
AllSources &allSources{cooked_.allSources()};
startProvenance_ = range.start();
std::size_t offset{0};
const SourceFile *source{allSources.GetSourceFile(startProvenance_, &offset)};
CHECK(source);
start_ = source->content().data() + offset;
limit_ = start_ + range.size();
nextLine_ = start_;
const bool beganInFixedForm{inFixedForm_};
if (prescannerNesting_ > maxPrescannerNesting) {
Say(GetProvenance(start_),
"too many nested INCLUDE/#include files, possibly circular"_err_en_US);
return;
}
while (nextLine_ < limit_) {
Statement();
}
if (inFixedForm_ != beganInFixedForm) {
std::string dir{"!dir$ "};
if (beganInFixedForm) {
dir += "fixed";
} else {
dir += "free";
}
dir += '\n';
TokenSequence tokens{dir, allSources.AddCompilerInsertion(dir).start()};
tokens.Emit(cooked_);
}
}
void Prescanner::Statement() {
TokenSequence tokens;
LineClassification line{ClassifyLine(nextLine_)};
switch (line.kind) {
case LineClassification::Kind::Comment:
nextLine_ += line.payloadOffset; // advance to '!' or newline
NextLine();
return;
case LineClassification::Kind::IncludeLine:
FortranInclude(nextLine_ + line.payloadOffset);
NextLine();
return;
case LineClassification::Kind::ConditionalCompilationDirective:
case LineClassification::Kind::IncludeDirective:
case LineClassification::Kind::DefinitionDirective:
case LineClassification::Kind::PreprocessorDirective:
preprocessor_.Directive(TokenizePreprocessorDirective(), this);
return;
case LineClassification::Kind::CompilerDirective:
directiveSentinel_ = line.sentinel;
CHECK(InCompilerDirective());
BeginStatementAndAdvance();
if (inFixedForm_) {
CHECK(IsFixedFormCommentChar(*at_));
} else {
while (*at_ == ' ' || *at_ == '\t') {
++at_, ++column_;
}
CHECK(*at_ == '!');
}
if (directiveSentinel_[0] == '$' && directiveSentinel_[1] == '\0') {
// OpenMP conditional compilation line. Remove the sentinel and then
// treat the line as if it were normal source.
at_ += 2, column_ += 2;
if (inFixedForm_) {
LabelField(tokens);
} else {
SkipSpaces();
}
} else {
// Compiler directive. Emit normalized sentinel.
EmitChar(tokens, '!');
++at_, ++column_;
for (const char *sp{directiveSentinel_}; *sp != '\0';
++sp, ++at_, ++column_) {
EmitChar(tokens, *sp);
}
if (*at_ == ' ') {
EmitChar(tokens, ' ');
++at_, ++column_;
}
tokens.CloseToken();
}
break;
case LineClassification::Kind::Source:
BeginStatementAndAdvance();
if (inFixedForm_) {
LabelField(tokens);
} else if (skipLeadingAmpersand_) {
skipLeadingAmpersand_ = false;
const char *p{SkipWhiteSpace(at_)};
if (p < limit_ && *p == '&') {
column_ += ++p - at_;
at_ = p;
}
} else {
SkipSpaces();
}
break;
}
while (NextToken(tokens)) {
}
Provenance newlineProvenance{GetCurrentProvenance()};
if (std::optional<TokenSequence> preprocessed{
preprocessor_.MacroReplacement(tokens, *this)}) {
// Reprocess the preprocessed line. Append a newline temporarily.
preprocessed->PutNextTokenChar('\n', newlineProvenance);
preprocessed->CloseToken();
const char *ppd{preprocessed->ToCharBlock().begin()};
LineClassification ppl{ClassifyLine(ppd)};
preprocessed->RemoveLastToken(); // remove the newline
switch (ppl.kind) {
case LineClassification::Kind::Comment:
break;
case LineClassification::Kind::IncludeLine:
FortranInclude(ppd + ppl.payloadOffset);
break;
case LineClassification::Kind::ConditionalCompilationDirective:
case LineClassification::Kind::IncludeDirective:
case LineClassification::Kind::DefinitionDirective:
case LineClassification::Kind::PreprocessorDirective:
Say(preprocessed->GetProvenanceRange(),
"Preprocessed line resembles a preprocessor directive"_en_US);
preprocessed->ToLowerCase().Emit(cooked_);
break;
case LineClassification::Kind::CompilerDirective:
if (preprocessed->HasRedundantBlanks()) {
preprocessed->RemoveRedundantBlanks();
}
NormalizeCompilerDirectiveCommentMarker(*preprocessed);
preprocessed->ToLowerCase();
SourceFormChange(preprocessed->ToString());
preprocessed->ClipComment(true /* skip first ! */).Emit(cooked_);
break;
case LineClassification::Kind::Source:
if (inFixedForm_) {
if (preprocessed->HasBlanks(/*after column*/ 6)) {
preprocessed->RemoveBlanks(/*after column*/ 6);
}
} else {
if (preprocessed->HasRedundantBlanks()) {
preprocessed->RemoveRedundantBlanks();
}
}
preprocessed->ToLowerCase().ClipComment().Emit(cooked_);
break;
}
} else {
tokens.ToLowerCase();
if (line.kind == LineClassification::Kind::CompilerDirective) {
SourceFormChange(tokens.ToString());
}
tokens.Emit(cooked_);
}
if (omitNewline_) {
omitNewline_ = false;
} else {
cooked_.Put('\n', newlineProvenance);
}
directiveSentinel_ = nullptr;
}
TokenSequence Prescanner::TokenizePreprocessorDirective() {
CHECK(nextLine_ < limit_ && !inPreprocessorDirective_);
inPreprocessorDirective_ = true;
BeginStatementAndAdvance();
TokenSequence tokens;
while (NextToken(tokens)) {
}
inPreprocessorDirective_ = false;
return tokens;
}
void Prescanner::NextLine() {
void *vstart{static_cast<void *>(const_cast<char *>(nextLine_))};
void *v{std::memchr(vstart, '\n', limit_ - nextLine_)};
if (!v) {
nextLine_ = limit_;
} else {
const char *nl{const_cast<const char *>(static_cast<char *>(v))};
nextLine_ = nl + 1;
}
}
void Prescanner::LabelField(TokenSequence &token) {
const char *bad{nullptr};
int outCol{1};
for (; *at_ != '\n' && column_ <= 6; ++at_) {
if (*at_ == '\t') {
++at_;
column_ = 7;
break;
}
if (*at_ != ' ' &&
!(*at_ == '0' && column_ == 6)) { // '0' in column 6 becomes space
EmitChar(token, *at_);
++outCol;
if (!bad && !IsDecimalDigit(*at_)) {
bad = at_;
}
}
++column_;
}
if (outCol == 1) { // empty label field
// Emit a space so that, if the line is rescanned after preprocessing,
// a leading 'C' or 'D' won't be left-justified and then accidentally
// misinterpreted as a comment card.
EmitChar(token, ' ');
++outCol;
} else {
if (bad && !preprocessor_.IsNameDefined(token.CurrentOpenToken())) {
Say(GetProvenance(bad),
"Character in fixed-form label field must be a digit"_en_US);
}
}
token.CloseToken();
SkipToNextSignificantCharacter();
if (IsDecimalDigit(*at_)) {
Say(GetProvenance(at_),
"Label digit is not in fixed-form label field"_en_US);
}
}
void Prescanner::SkipToEndOfLine() {
while (*at_ != '\n') {
++at_, ++column_;
}
}
bool Prescanner::MustSkipToEndOfLine() const {
if (inFixedForm_ && column_ > fixedFormColumnLimit_ && !tabInCurrentLine_) {
return true; // skip over ignored columns in right margin (73:80)
} else if (*at_ == '!' && !inCharLiteral_) {
return true; // inline comment goes to end of source line
} else {
return false;
}
}
void Prescanner::NextChar() {
CHECK(*at_ != '\n');
++at_, ++column_;
while (at_[0] == '\xef' && at_[1] == '\xbb' && at_[2] == '\xbf') {
// UTF-8 byte order mark - treat this file as UTF-8
at_ += 3;
encoding_ = Encoding::UTF_8;
}
SkipToNextSignificantCharacter();
}
// Skip everything that should be ignored until the next significant
// character is reached; handles C-style comments in preprocessing
// directives, Fortran ! comments, stuff after the right margin in
// fixed form, and all forms of line continuation.
void Prescanner::SkipToNextSignificantCharacter() {
if (inPreprocessorDirective_) {
SkipCComments();
} else {
bool mightNeedSpace{false};
if (MustSkipToEndOfLine()) {
SkipToEndOfLine();
} else {
mightNeedSpace = *at_ == '\n';
}
for (; Continuation(mightNeedSpace); mightNeedSpace = false) {
if (MustSkipToEndOfLine()) {
SkipToEndOfLine();
}
}
if (*at_ == '\t') {
tabInCurrentLine_ = true;
}
}
}
void Prescanner::SkipCComments() {
while (true) {
if (IsCComment(at_)) {
if (const char *after{SkipCComment(at_)}) {
column_ += after - at_;
// May have skipped over one or more newlines; relocate the start of
// the next line.
nextLine_ = at_ = after;
NextLine();
} else {
// Don't emit any messages about unclosed C-style comments, because
// the sequence /* can appear legally in a FORMAT statement. There's
// no ambiguity, since the sequence */ cannot appear legally.
break;
}
} else if (inPreprocessorDirective_ && at_[0] == '\\' && at_ + 2 < limit_ &&
at_[1] == '\n' && nextLine_ < limit_) {
BeginSourceLineAndAdvance();
} else {
break;
}
}
}
void Prescanner::SkipSpaces() {
while (*at_ == ' ' || *at_ == '\t') {
NextChar();
}
insertASpace_ = false;
}
const char *Prescanner::SkipWhiteSpace(const char *p) {
while (*p == ' ' || *p == '\t') {
++p;
}
return p;
}
const char *Prescanner::SkipWhiteSpaceAndCComments(const char *p) const {
while (true) {
if (*p == ' ' || *p == '\t') {
++p;
} else if (IsCComment(p)) {
if (const char *after{SkipCComment(p)}) {
p = after;
} else {
break;
}
} else {
break;
}
}
return p;
}
const char *Prescanner::SkipCComment(const char *p) const {
char star{' '}, slash{' '};
p += 2;
while (star != '*' || slash != '/') {
if (p >= limit_) {
return nullptr; // signifies an unterminated comment
}
star = slash;
slash = *p++;
}
return p;
}
bool Prescanner::NextToken(TokenSequence &tokens) {
CHECK(at_ >= start_ && at_ < limit_);
if (InFixedFormSource()) {
SkipSpaces();
} else {
if (*at_ == '/' && IsCComment(at_)) {
// Recognize and skip over classic C style /*comments*/ when
// outside a character literal.
if (features_.ShouldWarn(LanguageFeature::ClassicCComments)) {
Say(GetProvenance(at_), "nonstandard usage: C-style comment"_en_US);
}
SkipCComments();
}
if (*at_ == ' ' || *at_ == '\t') {
// Compress free-form white space into a single space character.
const auto theSpace{at_};
char previous{at_ <= start_ ? ' ' : at_[-1]};
NextChar();
SkipSpaces();
if (*at_ == '\n') {
// Discard white space at the end of a line.
} else if (!inPreprocessorDirective_ &&
(previous == '(' || *at_ == '(' || *at_ == ')')) {
// Discard white space before/after '(' and before ')', unless in a
// preprocessor directive. This helps yield space-free contiguous
// names for generic interfaces like OPERATOR( + ) and
// READ ( UNFORMATTED ), without misinterpreting #define f (notAnArg).
// This has the effect of silently ignoring the illegal spaces in
// the array constructor ( /1,2/ ) but that seems benign; it's
// hard to avoid that while still removing spaces from OPERATOR( / )
// and OPERATOR( // ).
} else {
// Preserve the squashed white space as a single space character.
tokens.PutNextTokenChar(' ', GetProvenance(theSpace));
tokens.CloseToken();
return true;
}
}
}
if (insertASpace_) {
tokens.PutNextTokenChar(' ', spaceProvenance_);
insertASpace_ = false;
}
if (*at_ == '\n') {
return false;
}
const char *start{at_};
if (*at_ == '\'' || *at_ == '"') {
QuotedCharacterLiteral(tokens, start);
preventHollerith_ = false;
} else if (IsDecimalDigit(*at_)) {
int n{0}, digits{0};
static constexpr int maxHollerith{256 /*lines*/ * (132 - 6 /*columns*/)};
do {
if (n < maxHollerith) {
n = 10 * n + DecimalDigitValue(*at_);
}
EmitCharAndAdvance(tokens, *at_);
++digits;
if (InFixedFormSource()) {
SkipSpaces();
}
} while (IsDecimalDigit(*at_));
if ((*at_ == 'h' || *at_ == 'H') && n > 0 && n < maxHollerith &&
!preventHollerith_) {
Hollerith(tokens, n, start);
} else if (*at_ == '.') {
while (IsDecimalDigit(EmitCharAndAdvance(tokens, *at_))) {
}
ExponentAndKind(tokens);
} else if (ExponentAndKind(tokens)) {
} else if (digits == 1 && n == 0 && (*at_ == 'x' || *at_ == 'X') &&
inPreprocessorDirective_) {
do {
EmitCharAndAdvance(tokens, *at_);
} while (IsHexadecimalDigit(*at_));
} else if (IsLetter(*at_)) {
// Handles FORMAT(3I9HHOLLERITH) by skipping over the first I so that
// we don't misrecognize I9HOLLERITH as an identifier in the next case.
EmitCharAndAdvance(tokens, *at_);
} else if (at_[0] == '_' && (at_[1] == '\'' || at_[1] == '"')) {
EmitCharAndAdvance(tokens, *at_);
QuotedCharacterLiteral(tokens, start);
}
preventHollerith_ = false;
} else if (*at_ == '.') {
char nch{EmitCharAndAdvance(tokens, '.')};
if (!inPreprocessorDirective_ && IsDecimalDigit(nch)) {
while (IsDecimalDigit(EmitCharAndAdvance(tokens, *at_))) {
}
ExponentAndKind(tokens);
} else if (nch == '.' && EmitCharAndAdvance(tokens, '.') == '.') {
EmitCharAndAdvance(tokens, '.'); // variadic macro definition ellipsis
}
preventHollerith_ = false;
} else if (IsLegalInIdentifier(*at_)) {
do {
} while (IsLegalInIdentifier(EmitCharAndAdvance(tokens, *at_)));
if (*at_ == '\'' || *at_ == '"') {
QuotedCharacterLiteral(tokens, start);
}
preventHollerith_ = false;
} else if (*at_ == '*') {
if (EmitCharAndAdvance(tokens, '*') == '*') {
EmitCharAndAdvance(tokens, '*');
} else {
// Subtle ambiguity:
// CHARACTER*2H declares H because *2 is a kind specifier
// DATAC/N*2H / is repeated Hollerith
preventHollerith_ = !slashInCurrentStatement_;
}
} else {
char ch{*at_};
if (ch == '(' || ch == '[') {
++delimiterNesting_;
} else if ((ch == ')' || ch == ']') && delimiterNesting_ > 0) {
--delimiterNesting_;
}
char nch{EmitCharAndAdvance(tokens, ch)};
preventHollerith_ = false;
if ((nch == '=' &&
(ch == '<' || ch == '>' || ch == '/' || ch == '=' || ch == '!')) ||
(ch == nch &&
(ch == '/' || ch == ':' || ch == '*' || ch == '#' || ch == '&' ||
ch == '|' || ch == '<' || ch == '>')) ||
(ch == '=' && nch == '>')) {
// token comprises two characters
EmitCharAndAdvance(tokens, nch);
} else if (ch == '/') {
slashInCurrentStatement_ = true;
}
}
tokens.CloseToken();
return true;
}
bool Prescanner::ExponentAndKind(TokenSequence &tokens) {
char ed{ToLowerCaseLetter(*at_)};
if (ed != 'e' && ed != 'd') {
return false;
}
EmitCharAndAdvance(tokens, ed);
if (*at_ == '+' || *at_ == '-') {
EmitCharAndAdvance(tokens, *at_);
}
while (IsDecimalDigit(*at_)) {
EmitCharAndAdvance(tokens, *at_);
}
if (*at_ == '_') {
while (IsLegalInIdentifier(EmitCharAndAdvance(tokens, *at_))) {
}
}
return true;
}
void Prescanner::QuotedCharacterLiteral(
TokenSequence &tokens, const char *start) {
char quote{*at_};
const char *end{at_ + 1};
inCharLiteral_ = true;
const auto emit{[&](char ch) { EmitChar(tokens, ch); }};
const auto insert{[&](char ch) { EmitInsertedChar(tokens, ch); }};
bool isEscaped{false};
bool escapesEnabled{features_.IsEnabled(LanguageFeature::BackslashEscapes)};
while (true) {
if (*at_ == '\\') {
if (escapesEnabled) {
isEscaped = !isEscaped;
} else {
// The parser always processes escape sequences, so don't confuse it
// when escapes are disabled.
insert('\\');
}
} else {
isEscaped = false;
}
EmitQuotedChar(static_cast<unsigned char>(*at_), emit, insert, false,
Encoding::LATIN_1);
while (PadOutCharacterLiteral(tokens)) {
}
if (*at_ == '\n') {
if (!inPreprocessorDirective_) {
Say(GetProvenanceRange(start, end),
"Incomplete character literal"_err_en_US);
}
break;
}
end = at_ + 1;
NextChar();
if (*at_ == quote && !isEscaped) {
// A doubled unescaped quote mark becomes a single instance of that
// quote character in the literal (later). There can be spaces between
// the quotes in fixed form source.
EmitChar(tokens, quote);
inCharLiteral_ = false; // for cases like print *, '...'!comment
NextChar();
if (InFixedFormSource()) {
SkipSpaces();
}
if (*at_ != quote) {
break;
}
inCharLiteral_ = true;
}
}
inCharLiteral_ = false;
}
void Prescanner::Hollerith(
TokenSequence &tokens, int count, const char *start) {
inCharLiteral_ = true;
CHECK(*at_ == 'h' || *at_ == 'H');
EmitChar(tokens, 'H');
while (count-- > 0) {
if (PadOutCharacterLiteral(tokens)) {
} else if (*at_ == '\n') {
Say(GetProvenanceRange(start, at_),
"Possible truncated Hollerith literal"_en_US);
break;
} else {
NextChar();
// Each multi-byte character encoding counts as a single character.
// No escape sequences are recognized.
// Hollerith is always emitted to the cooked character
// stream in UTF-8.
DecodedCharacter decoded{DecodeCharacter(
encoding_, at_, static_cast<std::size_t>(limit_ - at_), false)};
if (decoded.bytes > 0) {
EncodedCharacter utf8{
EncodeCharacter<Encoding::UTF_8>(decoded.codepoint)};
for (int j{0}; j < utf8.bytes; ++j) {
EmitChar(tokens, utf8.buffer[j]);
}
at_ += decoded.bytes - 1;
} else {
Say(GetProvenanceRange(start, at_),
"Bad character in Hollerith literal"_err_en_US);
break;
}
}
}
if (*at_ != '\n') {
NextChar();
}
inCharLiteral_ = false;
}
// In fixed form, source card images must be processed as if they were at
// least 72 columns wide, at least in character literal contexts.
bool Prescanner::PadOutCharacterLiteral(TokenSequence &tokens) {
while (inFixedForm_ && !tabInCurrentLine_ && at_[1] == '\n') {
if (column_ < fixedFormColumnLimit_) {
tokens.PutNextTokenChar(' ', spaceProvenance_);
++column_;
return true;
}
if (!FixedFormContinuation(false /*no need to insert space*/) ||
tabInCurrentLine_) {
return false;
}
CHECK(column_ == 7);
--at_; // point to column 6 of continuation line
column_ = 6;
}
return false;
}
bool Prescanner::IsFixedFormCommentLine(const char *start) const {
const char *p{start};
if (IsFixedFormCommentChar(*p) || *p == '%' || // VAX %list, %eject, &c.
((*p == 'D' || *p == 'd') &&
!features_.IsEnabled(LanguageFeature::OldDebugLines))) {
return true;
}
bool anyTabs{false};
while (true) {
if (*p == ' ') {
++p;
} else if (*p == '\t') {
anyTabs = true;
++p;
} else if (*p == '0' && !anyTabs && p == start + 5) {
++p; // 0 in column 6 must treated as a space
} else {
break;
}
}
if (!anyTabs && p >= start + fixedFormColumnLimit_) {
return true;
}
if (*p == '!' && !inCharLiteral_ && (anyTabs || p != start + 5)) {
return true;
}
return *p == '\n';
}
const char *Prescanner::IsFreeFormComment(const char *p) const {
p = SkipWhiteSpaceAndCComments(p);
if (*p == '!' || *p == '\n') {
return p;
} else {
return nullptr;
}
}
std::optional<std::size_t> Prescanner::IsIncludeLine(const char *start) const {
const char *p{SkipWhiteSpace(start)};
for (char ch : "include"s) {
if (ToLowerCaseLetter(*p++) != ch) {
return std::nullopt;
}
}
p = SkipWhiteSpace(p);
if (*p == '"' || *p == '\'') {
return {p - start};
}
return std::nullopt;
}
void Prescanner::FortranInclude(const char *firstQuote) {
const char *p{firstQuote};
while (*p != '"' && *p != '\'') {
++p;
}
char quote{*p};
std::string path;
for (++p; *p != '\n'; ++p) {
if (*p == quote) {
if (p[1] != quote) {
break;
}
++p;
}
path += *p;
}
if (*p != quote) {
Say(GetProvenanceRange(firstQuote, p),
"malformed path name string"_err_en_US);
return;
}
p = SkipWhiteSpace(p + 1);
if (*p != '\n' && *p != '!') {
const char *garbage{p};
for (; *p != '\n' && *p != '!'; ++p) {
}
Say(GetProvenanceRange(garbage, p),
"excess characters after path name"_en_US);
}
std::string buf;
llvm::raw_string_ostream error{buf};
Provenance provenance{GetProvenance(nextLine_)};
AllSources &allSources{cooked_.allSources()};
const SourceFile *currentFile{allSources.GetSourceFile(provenance)};
if (currentFile) {
allSources.PushSearchPathDirectory(DirectoryName(currentFile->path()));
}
const SourceFile *included{allSources.Open(path, error)};
if (currentFile) {
allSources.PopSearchPathDirectory();
}
if (!included) {
Say(provenance, "INCLUDE: %s"_err_en_US, error.str());
} else if (included->bytes() > 0) {
ProvenanceRange includeLineRange{
provenance, static_cast<std::size_t>(p - nextLine_)};
ProvenanceRange fileRange{
allSources.AddIncludedFile(*included, includeLineRange)};
Prescanner{*this}.set_encoding(included->encoding()).Prescan(fileRange);
}
}
const char *Prescanner::IsPreprocessorDirectiveLine(const char *start) const {
const char *p{start};
for (; *p == ' '; ++p) {
}
if (*p == '#') {
if (inFixedForm_ && p == start + 5) {
return nullptr;
}
} else {
p = SkipWhiteSpace(p);
if (*p != '#') {
return nullptr;
}
}
return SkipWhiteSpace(p + 1);
}
bool Prescanner::IsNextLinePreprocessorDirective() const {
return IsPreprocessorDirectiveLine(nextLine_) != nullptr;
}
bool Prescanner::SkipCommentLine(bool afterAmpersand) {
if (nextLine_ >= limit_) {
if (afterAmpersand && prescannerNesting_ > 0) {
// A continuation marker at the end of the last line in an
// include file inhibits the newline for that line.
SkipToEndOfLine();
omitNewline_ = true;
}
return false;
}
auto lineClass{ClassifyLine(nextLine_)};
if (lineClass.kind == LineClassification::Kind::Comment) {
NextLine();
return true;
} else if (inPreprocessorDirective_) {
return false;
} else if (lineClass.kind ==
LineClassification::Kind::ConditionalCompilationDirective ||
lineClass.kind == LineClassification::Kind::PreprocessorDirective) {
// Allow conditional compilation directives (e.g., #ifdef) to affect
// continuation lines.
// Allow other preprocessor directives, too, except #include
// (when it does not follow '&'), #define, and #undef (because
// they cannot be allowed to affect preceding text on a
// continued line).
preprocessor_.Directive(TokenizePreprocessorDirective(), this);
return true;
} else if (afterAmpersand &&
(lineClass.kind == LineClassification::Kind::IncludeDirective ||
lineClass.kind == LineClassification::Kind::IncludeLine)) {
SkipToEndOfLine();
omitNewline_ = true;
skipLeadingAmpersand_ = true;
return false;
} else {
return false;
}
}
const char *Prescanner::FixedFormContinuationLine(bool mightNeedSpace) {
if (nextLine_ >= limit_) {
return nullptr;
}
tabInCurrentLine_ = false;
char col1{*nextLine_};
if (InCompilerDirective()) {
// Must be a continued compiler directive.
if (!IsFixedFormCommentChar(col1)) {
return nullptr;
}
int j{1};
for (; j < 5; ++j) {
char ch{directiveSentinel_[j - 1]};
if (ch == '\0') {
break;
}
if (ch != ToLowerCaseLetter(nextLine_[j])) {
return nullptr;
}
}
for (; j < 5; ++j) {
if (nextLine_[j] != ' ') {
return nullptr;
}
}
char col6{nextLine_[5]};
if (col6 != '\n' && col6 != '\t' && col6 != ' ' && col6 != '0') {
if (nextLine_[6] != ' ' && mightNeedSpace) {
insertASpace_ = true;
}
return nextLine_ + 6;
}
return nullptr;
} else {
// Normal case: not in a compiler directive.
if (col1 == '&' &&
features_.IsEnabled(
LanguageFeature::FixedFormContinuationWithColumn1Ampersand)) {
// Extension: '&' as continuation marker
if (features_.ShouldWarn(
LanguageFeature::FixedFormContinuationWithColumn1Ampersand)) {
Say(GetProvenance(nextLine_), "nonstandard usage"_en_US);
}
return nextLine_ + 1;
}
if (col1 == '\t' && nextLine_[1] >= '1' && nextLine_[1] <= '9') {
tabInCurrentLine_ = true;
return nextLine_ + 2; // VAX extension
}
if (col1 == ' ' && nextLine_[1] == ' ' && nextLine_[2] == ' ' &&
nextLine_[3] == ' ' && nextLine_[4] == ' ') {
char col6{nextLine_[5]};
if (col6 != '\n' && col6 != '\t' && col6 != ' ' && col6 != '0') {
return nextLine_ + 6;
}
}
if (IsImplicitContinuation()) {
return nextLine_;
}
}
return nullptr; // not a continuation line
}
const char *Prescanner::FreeFormContinuationLine(bool ampersand) {
const char *p{nextLine_};
if (p >= limit_) {
return nullptr;
}
p = SkipWhiteSpace(p);
if (InCompilerDirective()) {
if (*p++ != '!') {
return nullptr;
}
for (const char *s{directiveSentinel_}; *s != '\0'; ++p, ++s) {
if (*s != ToLowerCaseLetter(*p)) {
return nullptr;
}
}
p = SkipWhiteSpace(p);
if (*p == '&') {
if (!ampersand) {
insertASpace_ = true;
}
return p + 1;
} else if (ampersand) {
return p;
} else {
return nullptr;
}
} else {
if (*p == '&') {
return p + 1;
} else if (*p == '!' || *p == '\n' || *p == '#') {
return nullptr;
} else if (ampersand || IsImplicitContinuation()) {
if (p > nextLine_) {
--p;
} else {
insertASpace_ = true;
}
return p;
} else {
return nullptr;
}
}
}
bool Prescanner::FixedFormContinuation(bool mightNeedSpace) {
// N.B. We accept '&' as a continuation indicator in fixed form, too,
// but not in a character literal.
if (*at_ == '&' && inCharLiteral_) {
return false;
}
do {
if (const char *cont{FixedFormContinuationLine(mightNeedSpace)}) {
BeginSourceLine(cont);
column_ = 7;
NextLine();
return true;
}
} while (SkipCommentLine(false /* not after ampersand */));
return false;
}
bool Prescanner::FreeFormContinuation() {
const char *p{at_};
bool ampersand{*p == '&'};
if (ampersand) {
p = SkipWhiteSpace(p + 1);
}
if (*p != '\n') {
if (inCharLiteral_) {
return false;
} else if (*p != '!' &&
features_.ShouldWarn(LanguageFeature::CruftAfterAmpersand)) {
Say(GetProvenance(p), "missing ! before comment after &"_en_US);
}
}
do {
if (const char *cont{FreeFormContinuationLine(ampersand)}) {
BeginSourceLine(cont);
NextLine();
return true;
}
} while (SkipCommentLine(ampersand));
return false;
}
// Implicit line continuation allows a preprocessor macro call with
// arguments to span multiple lines.
bool Prescanner::IsImplicitContinuation() const {
return !inPreprocessorDirective_ && !inCharLiteral_ &&
delimiterNesting_ > 0 && nextLine_ < limit_ &&
ClassifyLine(nextLine_).kind == LineClassification::Kind::Source;
}
bool Prescanner::Continuation(bool mightNeedFixedFormSpace) {
if (*at_ == '\n' || *at_ == '&') {
if (inFixedForm_) {
return FixedFormContinuation(mightNeedFixedFormSpace);
} else {
return FreeFormContinuation();
}
} else {
return false;
}
}
std::optional<Prescanner::LineClassification>
Prescanner::IsFixedFormCompilerDirectiveLine(const char *start) const {
const char *p{start};
char col1{*p++};
if (!IsFixedFormCommentChar(col1)) {
return std::nullopt;
}
char sentinel[5], *sp{sentinel};
int column{2};
for (; column < 6; ++column, ++p) {
if (*p != ' ') {
if (*p == '\n' || *p == '\t') {
break;
}
if (sp == sentinel + 1 && sentinel[0] == '$' && IsDecimalDigit(*p)) {
// OpenMP conditional compilation line: leave the label alone
break;
}
*sp++ = ToLowerCaseLetter(*p);
}
}
if (column == 6) {
if (*p == ' ' || *p == '\t' || *p == '0') {
++p;
} else {
// This is a Continuation line, not an initial directive line.
return std::nullopt;
}
}
if (sp == sentinel) {
return std::nullopt;
}
*sp = '\0';
if (const char *ss{IsCompilerDirectiveSentinel(sentinel)}) {
std::size_t payloadOffset = p - start;
return {LineClassification{
LineClassification::Kind::CompilerDirective, payloadOffset, ss}};
}
return std::nullopt;
}
std::optional<Prescanner::LineClassification>
Prescanner::IsFreeFormCompilerDirectiveLine(const char *start) const {
char sentinel[8];
const char *p{SkipWhiteSpace(start)};
if (*p++ != '!') {
return std::nullopt;
}
for (std::size_t j{0}; j + 1 < sizeof sentinel; ++p, ++j) {
if (*p == '\n') {
break;
}
if (*p == ' ' || *p == '\t' || *p == '&') {
if (j == 0) {
break;
}
sentinel[j] = '\0';
p = SkipWhiteSpace(p + 1);
if (*p == '!') {
break;
}
if (const char *sp{IsCompilerDirectiveSentinel(sentinel)}) {
std::size_t offset = p - start;
return {LineClassification{
LineClassification::Kind::CompilerDirective, offset, sp}};
}
break;
}
sentinel[j] = ToLowerCaseLetter(*p);
}
return std::nullopt;
}
Prescanner &Prescanner::AddCompilerDirectiveSentinel(const std::string &dir) {
std::uint64_t packed{0};
for (char ch : dir) {
packed = (packed << 8) | (ToLowerCaseLetter(ch) & 0xff);
}
compilerDirectiveBloomFilter_.set(packed % prime1);
compilerDirectiveBloomFilter_.set(packed % prime2);
compilerDirectiveSentinels_.insert(dir);
return *this;
}
const char *Prescanner::IsCompilerDirectiveSentinel(
const char *sentinel) const {
std::uint64_t packed{0};
std::size_t n{0};
for (; sentinel[n] != '\0'; ++n) {
packed = (packed << 8) | (sentinel[n] & 0xff);
}
if (n == 0 || !compilerDirectiveBloomFilter_.test(packed % prime1) ||
!compilerDirectiveBloomFilter_.test(packed % prime2)) {
return nullptr;
}
const auto iter{compilerDirectiveSentinels_.find(std::string(sentinel, n))};
return iter == compilerDirectiveSentinels_.end() ? nullptr : iter->c_str();
}
constexpr bool IsDirective(const char *match, const char *dir) {
for (; *match; ++match) {
if (*match != ToLowerCaseLetter(*dir++)) {
return false;
}
}
return true;
}
Prescanner::LineClassification Prescanner::ClassifyLine(
const char *start) const {
if (inFixedForm_) {
if (std::optional<LineClassification> lc{
IsFixedFormCompilerDirectiveLine(start)}) {
return std::move(*lc);
}
if (IsFixedFormCommentLine(start)) {
return {LineClassification::Kind::Comment};
}
} else {
if (std::optional<LineClassification> lc{
IsFreeFormCompilerDirectiveLine(start)}) {
return std::move(*lc);
}
if (const char *bang{IsFreeFormComment(start)}) {
return {LineClassification::Kind::Comment,
static_cast<std::size_t>(bang - start)};
}
}
if (std::optional<std::size_t> quoteOffset{IsIncludeLine(start)}) {
return {LineClassification::Kind::IncludeLine, *quoteOffset};
}
if (const char *dir{IsPreprocessorDirectiveLine(start)}) {
if (IsDirective("if", dir) || IsDirective("elif", dir) ||
IsDirective("else", dir) || IsDirective("endif", dir)) {
return {LineClassification::Kind::ConditionalCompilationDirective};
} else if (IsDirective("include", dir)) {
return {LineClassification::Kind::IncludeDirective};
} else if (IsDirective("define", dir) || IsDirective("undef", dir)) {
return {LineClassification::Kind::DefinitionDirective};
} else {
return {LineClassification::Kind::PreprocessorDirective};
}
}
return {LineClassification::Kind::Source};
}
void Prescanner::SourceFormChange(std::string &&dir) {
if (dir == "!dir$ free") {
inFixedForm_ = false;
} else if (dir == "!dir$ fixed") {
inFixedForm_ = true;
}
}
} // namespace Fortran::parser
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