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

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//===-- lib/Parser/preprocessor.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 "preprocessor.h"
#include "prescan.h"
#include "flang/Common/idioms.h"
#include "flang/Parser/characters.h"
#include "flang/Parser/message.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cinttypes>
#include <cstddef>
#include <ctime>
#include <map>
#include <memory>
#include <optional>
#include <set>
#include <utility>
namespace Fortran::parser {
Definition::Definition(
const TokenSequence &repl, std::size_t firstToken, std::size_t tokens)
: replacement_{Tokenize({}, repl, firstToken, tokens)} {}
Definition::Definition(const std::vector<std::string> &argNames,
const TokenSequence &repl, std::size_t firstToken, std::size_t tokens,
bool isVariadic)
: isFunctionLike_{true},
argumentCount_(argNames.size()), isVariadic_{isVariadic},
replacement_{Tokenize(argNames, repl, firstToken, tokens)} {}
Definition::Definition(const std::string &predefined, AllSources &sources)
: isPredefined_{true},
replacement_{
predefined, sources.AddCompilerInsertion(predefined).start()} {}
bool Definition::set_isDisabled(bool disable) {
bool was{isDisabled_};
isDisabled_ = disable;
return was;
}
static bool IsLegalIdentifierStart(const CharBlock &cpl) {
return cpl.size() > 0 && IsLegalIdentifierStart(cpl[0]);
}
TokenSequence Definition::Tokenize(const std::vector<std::string> &argNames,
const TokenSequence &token, std::size_t firstToken, std::size_t tokens) {
std::map<std::string, std::string> args;
char argIndex{'A'};
for (const std::string &arg : argNames) {
CHECK(args.find(arg) == args.end());
args[arg] = "~"s + argIndex++;
}
TokenSequence result;
for (std::size_t j{0}; j < tokens; ++j) {
CharBlock tok{token.TokenAt(firstToken + j)};
if (IsLegalIdentifierStart(tok)) {
auto it{args.find(tok.ToString())};
if (it != args.end()) {
result.Put(it->second, token.GetTokenProvenance(j));
continue;
}
}
result.Put(token, firstToken + j, 1);
}
return result;
}
static std::size_t AfterLastNonBlank(const TokenSequence &tokens) {
for (std::size_t j{tokens.SizeInTokens()}; j > 0; --j) {
if (!tokens.TokenAt(j - 1).IsBlank()) {
return j;
}
}
return 0;
}
static TokenSequence Stringify(
const TokenSequence &tokens, AllSources &allSources) {
TokenSequence result;
Provenance quoteProvenance{allSources.CompilerInsertionProvenance('"')};
result.PutNextTokenChar('"', quoteProvenance);
for (std::size_t j{0}; j < tokens.SizeInTokens(); ++j) {
const CharBlock &token{tokens.TokenAt(j)};
std::size_t bytes{token.size()};
for (std::size_t k{0}; k < bytes; ++k) {
char ch{token[k]};
Provenance from{tokens.GetTokenProvenance(j, k)};
if (ch == '"' || ch == '\\') {
result.PutNextTokenChar(ch, from);
}
result.PutNextTokenChar(ch, from);
}
}
result.PutNextTokenChar('"', quoteProvenance);
result.CloseToken();
return result;
}
TokenSequence Definition::Apply(
const std::vector<TokenSequence> &args, AllSources &allSources) {
TokenSequence result;
bool pasting{false};
bool skipping{false};
int parenthesesNesting{0};
std::size_t tokens{replacement_.SizeInTokens()};
for (std::size_t j{0}; j < tokens; ++j) {
const CharBlock &token{replacement_.TokenAt(j)};
std::size_t bytes{token.size()};
if (skipping) {
if (bytes == 1) {
if (token[0] == '(') {
++parenthesesNesting;
} else if (token[0] == ')') {
skipping = --parenthesesNesting > 0;
}
}
continue;
}
if (bytes == 2 && token[0] == '~') {
std::size_t index = token[1] - 'A';
if (index >= args.size()) {
continue;
}
std::size_t afterLastNonBlank{AfterLastNonBlank(result)};
if (afterLastNonBlank > 0 &&
result.TokenAt(afterLastNonBlank - 1).ToString() == "#") {
// stringifying
while (result.SizeInTokens() >= afterLastNonBlank) {
result.pop_back();
}
result.Put(Stringify(args[index], allSources));
} else {
std::size_t argTokens{args[index].SizeInTokens()};
for (std::size_t k{0}; k < argTokens; ++k) {
if (!pasting || !args[index].TokenAt(k).IsBlank()) {
result.Put(args[index], k);
pasting = false;
}
}
}
} else if (bytes == 2 && token[0] == '#' && token[1] == '#') {
// Token pasting operator in body (not expanded argument); discard any
// immediately preceding white space, then reopen the last token.
while (!result.empty() &&
result.TokenAt(result.SizeInTokens() - 1).IsBlank()) {
result.pop_back();
}
if (!result.empty()) {
result.ReopenLastToken();
pasting = true;
}
} else if (pasting && token.IsBlank()) {
// Delete whitespace immediately following ## in the body.
} else if (bytes == 11 && isVariadic_ &&
token.ToString() == "__VA_ARGS__") {
Provenance commaProvenance{allSources.CompilerInsertionProvenance(',')};
for (std::size_t k{argumentCount_}; k < args.size(); ++k) {
if (k > argumentCount_) {
result.Put(","s, commaProvenance);
}
result.Put(args[k]);
}
} else if (bytes == 10 && isVariadic_ && token.ToString() == "__VA_OPT__" &&
j + 2 < tokens && replacement_.TokenAt(j + 1).ToString() == "(" &&
parenthesesNesting == 0) {
parenthesesNesting = 1;
skipping = args.size() == argumentCount_;
++j;
} else {
if (bytes == 1 && parenthesesNesting > 0 && token[0] == '(') {
++parenthesesNesting;
} else if (bytes == 1 && parenthesesNesting > 0 && token[0] == ')') {
if (--parenthesesNesting == 0) {
skipping = false;
continue;
}
}
result.Put(replacement_, j);
}
}
return result;
}
static std::string FormatTime(const std::time_t &now, const char *format) {
char buffer[16];
return {buffer,
std::strftime(buffer, sizeof buffer, format, std::localtime(&now))};
}
Preprocessor::Preprocessor(AllSources &allSources) : allSources_{allSources} {
// Capture current local date & time once now to avoid having the values
// of __DATE__ or __TIME__ change during compilation.
std::time_t now;
std::time(&now);
definitions_.emplace(SaveTokenAsName("__DATE__"s), // e.g., "Jun 16 1904"
Definition{FormatTime(now, "\"%h %e %Y\""), allSources});
definitions_.emplace(SaveTokenAsName("__TIME__"s), // e.g., "23:59:60"
Definition{FormatTime(now, "\"%T\""), allSources});
// The values of these predefined macros depend on their invocation sites.
definitions_.emplace(
SaveTokenAsName("__FILE__"s), Definition{"__FILE__"s, allSources});
definitions_.emplace(
SaveTokenAsName("__LINE__"s), Definition{"__LINE__"s, allSources});
}
void Preprocessor::Define(std::string macro, std::string value) {
definitions_.emplace(SaveTokenAsName(macro), Definition{value, allSources_});
}
void Preprocessor::Undefine(std::string macro) { definitions_.erase(macro); }
std::optional<TokenSequence> Preprocessor::MacroReplacement(
const TokenSequence &input, const Prescanner &prescanner) {
// Do quick scan for any use of a defined name.
std::size_t tokens{input.SizeInTokens()};
std::size_t j;
for (j = 0; j < tokens; ++j) {
CharBlock token{input.TokenAt(j)};
if (!token.empty() && IsLegalIdentifierStart(token[0]) &&
IsNameDefined(token)) {
break;
}
}
if (j == tokens) {
return std::nullopt; // input contains nothing that would be replaced
}
TokenSequence result{input, 0, j};
for (; j < tokens; ++j) {
const CharBlock &token{input.TokenAt(j)};
if (token.IsBlank() || !IsLegalIdentifierStart(token[0])) {
result.Put(input, j);
continue;
}
auto it{definitions_.find(token)};
if (it == definitions_.end()) {
result.Put(input, j);
continue;
}
Definition &def{it->second};
if (def.isDisabled()) {
result.Put(input, j);
continue;
}
if (!def.isFunctionLike()) {
if (def.isPredefined()) {
std::string name{def.replacement().TokenAt(0).ToString()};
std::string repl;
if (name == "__FILE__") {
repl = "\""s +
allSources_.GetPath(prescanner.GetCurrentProvenance()) + '"';
} else if (name == "__LINE__") {
std::string buf;
llvm::raw_string_ostream ss{buf};
ss << allSources_.GetLineNumber(prescanner.GetCurrentProvenance());
repl = ss.str();
}
if (!repl.empty()) {
ProvenanceRange insert{allSources_.AddCompilerInsertion(repl)};
ProvenanceRange call{allSources_.AddMacroCall(
insert, input.GetTokenProvenanceRange(j), repl)};
result.Put(repl, call.start());
continue;
}
}
def.set_isDisabled(true);
TokenSequence replaced{ReplaceMacros(def.replacement(), prescanner)};
def.set_isDisabled(false);
if (!replaced.empty()) {
ProvenanceRange from{def.replacement().GetProvenanceRange()};
ProvenanceRange use{input.GetTokenProvenanceRange(j)};
ProvenanceRange newRange{
allSources_.AddMacroCall(from, use, replaced.ToString())};
result.Put(replaced, newRange);
}
continue;
}
// Possible function-like macro call. Skip spaces and newlines to see
// whether '(' is next.
std::size_t k{j};
bool leftParen{false};
while (++k < tokens) {
const CharBlock &lookAhead{input.TokenAt(k)};
if (!lookAhead.IsBlank() && lookAhead[0] != '\n') {
leftParen = lookAhead[0] == '(' && lookAhead.size() == 1;
break;
}
}
if (!leftParen) {
result.Put(input, j);
continue;
}
std::vector<std::size_t> argStart{++k};
for (int nesting{0}; k < tokens; ++k) {
CharBlock token{input.TokenAt(k)};
if (token.size() == 1) {
char ch{token[0]};
if (ch == '(') {
++nesting;
} else if (ch == ')') {
if (nesting == 0) {
break;
}
--nesting;
} else if (ch == ',' && nesting == 0) {
argStart.push_back(k + 1);
}
}
}
if (argStart.size() == 1 && k == argStart[0] && def.argumentCount() == 0) {
// Subtle: () is zero arguments, not one empty argument,
// unless one argument was expected.
argStart.clear();
}
if (k >= tokens || argStart.size() < def.argumentCount() ||
(argStart.size() > def.argumentCount() && !def.isVariadic())) {
result.Put(input, j);
continue;
}
std::vector<TokenSequence> args;
for (std::size_t n{0}; n < argStart.size(); ++n) {
std::size_t at{argStart[n]};
std::size_t count{
(n + 1 == argStart.size() ? k : argStart[n + 1] - 1) - at};
args.emplace_back(TokenSequence(input, at, count));
}
def.set_isDisabled(true);
TokenSequence replaced{
ReplaceMacros(def.Apply(args, allSources_), prescanner)};
def.set_isDisabled(false);
if (!replaced.empty()) {
ProvenanceRange from{def.replacement().GetProvenanceRange()};
ProvenanceRange use{input.GetIntervalProvenanceRange(j, k - j)};
ProvenanceRange newRange{
allSources_.AddMacroCall(from, use, replaced.ToString())};
result.Put(replaced, newRange);
}
j = k; // advance to the terminal ')'
}
return result;
}
TokenSequence Preprocessor::ReplaceMacros(
const TokenSequence &tokens, const Prescanner &prescanner) {
if (std::optional<TokenSequence> repl{MacroReplacement(tokens, prescanner)}) {
return std::move(*repl);
}
return tokens;
}
void Preprocessor::Directive(const TokenSequence &dir, Prescanner *prescanner) {
std::size_t tokens{dir.SizeInTokens()};
std::size_t j{dir.SkipBlanks(0)};
if (j == tokens) {
return;
}
if (dir.TokenAt(j).ToString() != "#") {
prescanner->Say(dir.GetTokenProvenanceRange(j), "missing '#'"_err_en_US);
return;
}
j = dir.SkipBlanks(j + 1);
while (tokens > 0 && dir.TokenAt(tokens - 1).IsBlank()) {
--tokens;
}
if (j == tokens) {
return;
}
if (IsDecimalDigit(dir.TokenAt(j)[0]) || dir.TokenAt(j)[0] == '"') {
return; // treat like #line, ignore it
}
std::size_t dirOffset{j};
std::string dirName{ToLowerCaseLetters(dir.TokenAt(dirOffset).ToString())};
j = dir.SkipBlanks(j + 1);
CharBlock nameToken;
if (j < tokens && IsLegalIdentifierStart(dir.TokenAt(j)[0])) {
nameToken = dir.TokenAt(j);
}
if (dirName == "line") {
// #line is ignored
} else if (dirName == "define") {
if (nameToken.empty()) {
prescanner->Say(dir.GetTokenProvenanceRange(j < tokens ? j : tokens - 1),
"#define: missing or invalid name"_err_en_US);
return;
}
nameToken = SaveTokenAsName(nameToken);
definitions_.erase(nameToken);
if (++j < tokens && dir.TokenAt(j).size() == 1 &&
dir.TokenAt(j)[0] == '(') {
j = dir.SkipBlanks(j + 1);
std::vector<std::string> argName;
bool isVariadic{false};
if (dir.TokenAt(j).ToString() != ")") {
while (true) {
std::string an{dir.TokenAt(j).ToString()};
if (an == "...") {
isVariadic = true;
} else {
if (an.empty() || !IsLegalIdentifierStart(an[0])) {
prescanner->Say(dir.GetTokenProvenanceRange(j),
"#define: missing or invalid argument name"_err_en_US);
return;
}
argName.push_back(an);
}
j = dir.SkipBlanks(j + 1);
if (j == tokens) {
prescanner->Say(dir.GetTokenProvenanceRange(tokens - 1),
"#define: malformed argument list"_err_en_US);
return;
}
std::string punc{dir.TokenAt(j).ToString()};
if (punc == ")") {
break;
}
if (isVariadic || punc != ",") {
prescanner->Say(dir.GetTokenProvenanceRange(j),
"#define: malformed argument list"_err_en_US);
return;
}
j = dir.SkipBlanks(j + 1);
if (j == tokens) {
prescanner->Say(dir.GetTokenProvenanceRange(tokens - 1),
"#define: malformed argument list"_err_en_US);
return;
}
}
if (std::set<std::string>(argName.begin(), argName.end()).size() !=
argName.size()) {
prescanner->Say(dir.GetTokenProvenance(dirOffset),
"#define: argument names are not distinct"_err_en_US);
return;
}
}
j = dir.SkipBlanks(j + 1);
definitions_.emplace(std::make_pair(
nameToken, Definition{argName, dir, j, tokens - j, isVariadic}));
} else {
j = dir.SkipBlanks(j + 1);
definitions_.emplace(
std::make_pair(nameToken, Definition{dir, j, tokens - j}));
}
} else if (dirName == "undef") {
if (nameToken.empty()) {
prescanner->Say(
dir.GetIntervalProvenanceRange(dirOffset, tokens - dirOffset),
"# missing or invalid name"_err_en_US);
} else {
j = dir.SkipBlanks(j + 1);
if (j != tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#undef: excess tokens at end of directive"_err_en_US);
} else {
definitions_.erase(nameToken);
}
}
} else if (dirName == "ifdef" || dirName == "ifndef") {
bool doThen{false};
if (nameToken.empty()) {
prescanner->Say(
dir.GetIntervalProvenanceRange(dirOffset, tokens - dirOffset),
"#%s: missing name"_err_en_US, dirName);
} else {
j = dir.SkipBlanks(j + 1);
if (j != tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#%s: excess tokens at end of directive"_en_US, dirName);
}
doThen = IsNameDefined(nameToken) == (dirName == "ifdef");
}
if (doThen) {
ifStack_.push(CanDeadElseAppear::Yes);
} else {
SkipDisabledConditionalCode(dirName, IsElseActive::Yes, prescanner,
dir.GetTokenProvenance(dirOffset));
}
} else if (dirName == "if") {
if (IsIfPredicateTrue(dir, j, tokens - j, prescanner)) {
ifStack_.push(CanDeadElseAppear::Yes);
} else {
SkipDisabledConditionalCode(dirName, IsElseActive::Yes, prescanner,
dir.GetTokenProvenanceRange(dirOffset));
}
} else if (dirName == "else") {
if (j != tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#else: excess tokens at end of directive"_err_en_US);
} else if (ifStack_.empty()) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#else: not nested within #if, #ifdef, or #ifndef"_err_en_US);
} else if (ifStack_.top() != CanDeadElseAppear::Yes) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#else: already appeared within this #if, #ifdef, or #ifndef"_err_en_US);
} else {
ifStack_.pop();
SkipDisabledConditionalCode("else", IsElseActive::No, prescanner,
dir.GetTokenProvenanceRange(dirOffset));
}
} else if (dirName == "elif") {
if (ifStack_.empty()) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#elif: not nested within #if, #ifdef, or #ifndef"_err_en_US);
} else if (ifStack_.top() != CanDeadElseAppear::Yes) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#elif: #else previously appeared within this #if, #ifdef, or #ifndef"_err_en_US);
} else {
ifStack_.pop();
SkipDisabledConditionalCode("elif", IsElseActive::No, prescanner,
dir.GetTokenProvenanceRange(dirOffset));
}
} else if (dirName == "endif") {
if (j != tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#endif: excess tokens at end of directive"_err_en_US);
} else if (ifStack_.empty()) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#endif: no #if, #ifdef, or #ifndef"_err_en_US);
} else {
ifStack_.pop();
}
} else if (dirName == "error") {
prescanner->Say(
dir.GetIntervalProvenanceRange(dirOffset, tokens - dirOffset),
"%s"_err_en_US, dir.ToString());
} else if (dirName == "warning" || dirName == "comment" ||
dirName == "note") {
prescanner->Say(
dir.GetIntervalProvenanceRange(dirOffset, tokens - dirOffset),
"%s"_en_US, dir.ToString());
} else if (dirName == "include") {
if (j == tokens) {
prescanner->Say(
dir.GetIntervalProvenanceRange(dirOffset, tokens - dirOffset),
"#include: missing name of file to include"_err_en_US);
return;
}
std::string include;
if (dir.TokenAt(j).ToString() == "<") {
std::size_t k{j + 1};
if (k >= tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#include: file name missing"_err_en_US);
return;
}
while (k < tokens && dir.TokenAt(k) != ">") {
++k;
}
if (k >= tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(j, tokens - j),
"#include: expected '>' at end of included file"_en_US);
} else if (k + 1 < tokens) {
prescanner->Say(dir.GetIntervalProvenanceRange(k + 1, tokens - k - 1),
"#include: extra stuff ignored after '>'"_en_US);
}
TokenSequence braced{dir, j + 1, k - j - 1};
include = ReplaceMacros(braced, *prescanner).ToString();
} else if (j + 1 == tokens &&
(include = dir.TokenAt(j).ToString()).substr(0, 1) == "\"" &&
include.substr(include.size() - 1, 1) == "\"") {
include = include.substr(1, include.size() - 2);
} else {
prescanner->Say(dir.GetTokenProvenanceRange(j < tokens ? j : tokens - 1),
"#include: expected name of file to include"_err_en_US);
return;
}
if (include.empty()) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#include: empty include file name"_err_en_US);
return;
}
std::string buf;
llvm::raw_string_ostream error{buf};
const SourceFile *included{allSources_.Open(include, error)};
if (!included) {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#include: %s"_err_en_US, error.str());
} else if (included->bytes() > 0) {
ProvenanceRange fileRange{
allSources_.AddIncludedFile(*included, dir.GetProvenanceRange())};
Prescanner{*prescanner}
.set_encoding(included->encoding())
.Prescan(fileRange);
}
} else {
prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
"#%s: unknown or unimplemented directive"_err_en_US, dirName);
}
}
CharBlock Preprocessor::SaveTokenAsName(const CharBlock &t) {
names_.push_back(t.ToString());
return {names_.back().data(), names_.back().size()};
}
bool Preprocessor::IsNameDefined(const CharBlock &token) {
return definitions_.find(token) != definitions_.end();
}
static std::string GetDirectiveName(
const TokenSequence &line, std::size_t *rest) {
std::size_t tokens{line.SizeInTokens()};
std::size_t j{line.SkipBlanks(0)};
if (j == tokens || line.TokenAt(j).ToString() != "#") {
*rest = tokens;
return "";
}
j = line.SkipBlanks(j + 1);
if (j == tokens) {
*rest = tokens;
return "";
}
*rest = line.SkipBlanks(j + 1);
return ToLowerCaseLetters(line.TokenAt(j).ToString());
}
void Preprocessor::SkipDisabledConditionalCode(const std::string &dirName,
IsElseActive isElseActive, Prescanner *prescanner,
ProvenanceRange provenanceRange) {
int nesting{0};
while (!prescanner->IsAtEnd()) {
if (!prescanner->IsNextLinePreprocessorDirective()) {
prescanner->NextLine();
continue;
}
TokenSequence line{prescanner->TokenizePreprocessorDirective()};
std::size_t rest{0};
std::string dn{GetDirectiveName(line, &rest)};
if (dn == "ifdef" || dn == "ifndef" || dn == "if") {
++nesting;
} else if (dn == "endif") {
if (nesting-- == 0) {
return;
}
} else if (isElseActive == IsElseActive::Yes && nesting == 0) {
if (dn == "else") {
ifStack_.push(CanDeadElseAppear::No);
return;
}
if (dn == "elif" &&
IsIfPredicateTrue(
line, rest, line.SizeInTokens() - rest, prescanner)) {
ifStack_.push(CanDeadElseAppear::Yes);
return;
}
}
}
prescanner->Say(provenanceRange, "#%s: missing #endif"_err_en_US, dirName);
}
// Precedence level codes used here to accommodate mixed Fortran and C:
// 15: parentheses and constants, logical !, bitwise ~
// 14: unary + and -
// 13: **
// 12: *, /, % (modulus)
// 11: + and -
// 10: << and >>
// 9: bitwise &
// 8: bitwise ^
// 7: bitwise |
// 6: relations (.EQ., ==, &c.)
// 5: .NOT.
// 4: .AND., &&
// 3: .OR., ||
// 2: .EQV. and .NEQV. / .XOR.
// 1: ? :
// 0: ,
static std::int64_t ExpressionValue(const TokenSequence &token,
int minimumPrecedence, std::size_t *atToken,
std::optional<Message> *error) {
enum Operator {
PARENS,
CONST,
NOTZERO, // !
COMPLEMENT, // ~
UPLUS,
UMINUS,
POWER,
TIMES,
DIVIDE,
MODULUS,
ADD,
SUBTRACT,
LEFTSHIFT,
RIGHTSHIFT,
BITAND,
BITXOR,
BITOR,
LT,
LE,
EQ,
NE,
GE,
GT,
NOT,
AND,
OR,
EQV,
NEQV,
SELECT,
COMMA
};
static const int precedence[]{
15, 15, 15, 15, // (), 6, !, ~
14, 14, // unary +, -
13, 12, 12, 12, 11, 11, 10, 10, // **, *, /, %, +, -, <<, >>
9, 8, 7, // &, ^, |
6, 6, 6, 6, 6, 6, // relations .LT. to .GT.
5, 4, 3, 2, 2, // .NOT., .AND., .OR., .EQV., .NEQV.
1, 0 // ?: and ,
};
static const int operandPrecedence[]{0, -1, 15, 15, 15, 15, 13, 12, 12, 12,
11, 11, 11, 11, 9, 8, 7, 7, 7, 7, 7, 7, 7, 6, 4, 3, 3, 3, 1, 0};
static std::map<std::string, enum Operator> opNameMap;
if (opNameMap.empty()) {
opNameMap["("] = PARENS;
opNameMap["!"] = NOTZERO;
opNameMap["~"] = COMPLEMENT;
opNameMap["**"] = POWER;
opNameMap["*"] = TIMES;
opNameMap["/"] = DIVIDE;
opNameMap["%"] = MODULUS;
opNameMap["+"] = ADD;
opNameMap["-"] = SUBTRACT;
opNameMap["<<"] = LEFTSHIFT;
opNameMap[">>"] = RIGHTSHIFT;
opNameMap["&"] = BITAND;
opNameMap["^"] = BITXOR;
opNameMap["|"] = BITOR;
opNameMap[".lt."] = opNameMap["<"] = LT;
opNameMap[".le."] = opNameMap["<="] = LE;
opNameMap[".eq."] = opNameMap["=="] = EQ;
opNameMap[".ne."] = opNameMap["/="] = opNameMap["!="] = NE;
opNameMap[".ge."] = opNameMap[">="] = GE;
opNameMap[".gt."] = opNameMap[">"] = GT;
opNameMap[".not."] = NOT;
opNameMap[".and."] = opNameMap[".a."] = opNameMap["&&"] = AND;
opNameMap[".or."] = opNameMap[".o."] = opNameMap["||"] = OR;
opNameMap[".eqv."] = EQV;
opNameMap[".neqv."] = opNameMap[".xor."] = opNameMap[".x."] = NEQV;
opNameMap["?"] = SELECT;
opNameMap[","] = COMMA;
}
std::size_t tokens{token.SizeInTokens()};
CHECK(tokens > 0);
if (*atToken >= tokens) {
*error =
Message{token.GetProvenanceRange(), "incomplete expression"_err_en_US};
return 0;
}
// Parse and evaluate a primary or a unary operator and its operand.
std::size_t opAt{*atToken};
std::string t{token.TokenAt(opAt).ToString()};
enum Operator op;
std::int64_t left{0};
if (t == "(") {
op = PARENS;
} else if (IsDecimalDigit(t[0])) {
op = CONST;
std::size_t consumed{0};
left = std::stoll(t, &consumed, 0 /*base to be detected*/);
if (consumed < t.size()) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"Uninterpretable numeric constant '%s'"_err_en_US, t};
return 0;
}
} else if (IsLegalIdentifierStart(t[0])) {
// undefined macro name -> zero
// TODO: BOZ constants?
op = CONST;
} else if (t == "+") {
op = UPLUS;
} else if (t == "-") {
op = UMINUS;
} else if (t == "." && *atToken + 2 < tokens &&
ToLowerCaseLetters(token.TokenAt(*atToken + 1).ToString()) == "not" &&
token.TokenAt(*atToken + 2).ToString() == ".") {
op = NOT;
*atToken += 2;
} else {
auto it{opNameMap.find(t)};
if (it != opNameMap.end()) {
op = it->second;
} else {
*error = Message{token.GetTokenProvenanceRange(opAt),
"operand expected in expression"_err_en_US};
return 0;
}
}
if (precedence[op] < minimumPrecedence) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"operator precedence error"_err_en_US};
return 0;
}
++*atToken;
if (op != CONST) {
left = ExpressionValue(token, operandPrecedence[op], atToken, error);
if (*error) {
return 0;
}
switch (op) {
case PARENS:
if (*atToken < tokens && token.TokenAt(*atToken).ToString() == ")") {
++*atToken;
break;
}
if (*atToken >= tokens) {
*error = Message{token.GetProvenanceRange(),
"')' missing from expression"_err_en_US};
} else {
*error = Message{
token.GetTokenProvenanceRange(*atToken), "expected ')'"_err_en_US};
}
return 0;
case NOTZERO:
left = !left;
break;
case COMPLEMENT:
left = ~left;
break;
case UPLUS:
break;
case UMINUS:
left = -left;
break;
case NOT:
left = -!left;
break;
default:
CRASH_NO_CASE;
}
}
// Parse and evaluate binary operators and their second operands, if present.
while (*atToken < tokens) {
int advance{1};
t = token.TokenAt(*atToken).ToString();
if (t == "." && *atToken + 2 < tokens &&
token.TokenAt(*atToken + 2).ToString() == ".") {
t += ToLowerCaseLetters(token.TokenAt(*atToken + 1).ToString()) + '.';
advance = 3;
}
auto it{opNameMap.find(t)};
if (it == opNameMap.end()) {
break;
}
op = it->second;
if (op < POWER || precedence[op] < minimumPrecedence) {
break;
}
opAt = *atToken;
*atToken += advance;
std::int64_t right{
ExpressionValue(token, operandPrecedence[op], atToken, error)};
if (*error) {
return 0;
}
switch (op) {
case POWER:
if (left == 0) {
if (right < 0) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"0 ** negative power"_err_en_US};
}
} else if (left != 1 && right != 1) {
if (right <= 0) {
left = !right;
} else {
std::int64_t power{1};
for (; right > 0; --right) {
if ((power * left) / left != power) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"overflow in exponentation"_err_en_US};
left = 1;
}
power *= left;
}
left = power;
}
}
break;
case TIMES:
if (left != 0 && right != 0 && ((left * right) / left) != right) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"overflow in multiplication"_err_en_US};
}
left = left * right;
break;
case DIVIDE:
if (right == 0) {
*error = Message{
token.GetTokenProvenanceRange(opAt), "division by zero"_err_en_US};
left = 0;
} else {
left = left / right;
}
break;
case MODULUS:
if (right == 0) {
*error = Message{
token.GetTokenProvenanceRange(opAt), "modulus by zero"_err_en_US};
left = 0;
} else {
left = left % right;
}
break;
case ADD:
if ((left < 0) == (right < 0) && (left < 0) != (left + right < 0)) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"overflow in addition"_err_en_US};
}
left = left + right;
break;
case SUBTRACT:
if ((left < 0) != (right < 0) && (left < 0) == (left - right < 0)) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"overflow in subtraction"_err_en_US};
}
left = left - right;
break;
case LEFTSHIFT:
if (right < 0 || right > 64) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"bad left shift count"_err_en_US};
}
left = right >= 64 ? 0 : left << right;
break;
case RIGHTSHIFT:
if (right < 0 || right > 64) {
*error = Message{token.GetTokenProvenanceRange(opAt),
"bad right shift count"_err_en_US};
}
left = right >= 64 ? 0 : left >> right;
break;
case BITAND:
case AND:
left = left & right;
break;
case BITXOR:
left = left ^ right;
break;
case BITOR:
case OR:
left = left | right;
break;
case LT:
left = -(left < right);
break;
case LE:
left = -(left <= right);
break;
case EQ:
left = -(left == right);
break;
case NE:
left = -(left != right);
break;
case GE:
left = -(left >= right);
break;
case GT:
left = -(left > right);
break;
case EQV:
left = -(!left == !right);
break;
case NEQV:
left = -(!left != !right);
break;
case SELECT:
if (*atToken >= tokens || token.TokenAt(*atToken).ToString() != ":") {
*error = Message{token.GetTokenProvenanceRange(opAt),
"':' required in selection expression"_err_en_US};
return 0;
} else {
++*atToken;
std::int64_t third{
ExpressionValue(token, operandPrecedence[op], atToken, error)};
left = left != 0 ? right : third;
}
break;
case COMMA:
left = right;
break;
default:
CRASH_NO_CASE;
}
}
return left;
}
bool Preprocessor::IsIfPredicateTrue(const TokenSequence &expr,
std::size_t first, std::size_t exprTokens, Prescanner *prescanner) {
TokenSequence expr1{expr, first, exprTokens};
if (expr1.HasBlanks()) {
expr1.RemoveBlanks();
}
TokenSequence expr2;
for (std::size_t j{0}; j < expr1.SizeInTokens(); ++j) {
if (ToLowerCaseLetters(expr1.TokenAt(j).ToString()) == "defined") {
CharBlock name;
if (j + 3 < expr1.SizeInTokens() &&
expr1.TokenAt(j + 1).ToString() == "(" &&
expr1.TokenAt(j + 3).ToString() == ")") {
name = expr1.TokenAt(j + 2);
j += 3;
} else if (j + 1 < expr1.SizeInTokens() &&
IsLegalIdentifierStart(expr1.TokenAt(j + 1))) {
name = expr1.TokenAt(++j);
}
if (!name.empty()) {
char truth{IsNameDefined(name) ? '1' : '0'};
expr2.Put(&truth, 1, allSources_.CompilerInsertionProvenance(truth));
continue;
}
}
expr2.Put(expr1, j);
}
TokenSequence expr3{ReplaceMacros(expr2, *prescanner)};
if (expr3.HasBlanks()) {
expr3.RemoveBlanks();
}
if (expr3.empty()) {
prescanner->Say(expr.GetProvenanceRange(), "empty expression"_err_en_US);
return false;
}
std::size_t atToken{0};
std::optional<Message> error;
bool result{ExpressionValue(expr3, 0, &atToken, &error) != 0};
if (error) {
prescanner->Say(std::move(*error));
} else if (atToken < expr3.SizeInTokens() &&
expr3.TokenAt(atToken).ToString() != "!") {
prescanner->Say(expr3.GetIntervalProvenanceRange(
atToken, expr3.SizeInTokens() - atToken),
atToken == 0 ? "could not parse any expression"_err_en_US
: "excess characters after expression"_err_en_US);
}
return result;
}
} // namespace Fortran::parser
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