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#include "cps/Preprocessor.h"
#include "cps/Diagnostics.h"
#include <string_view>
#include <unordered_set>
using namespace cps;
namespace {
bool nameStart(char C) {
return (C >= 'A' && C <= 'Z') || (C >= 'a' && C <= 'z') || C == '_';
}
bool nameContinue(char C) {
return nameStart(C) || (C >= '0' && C <= '9');
}
std::string_view trim(std::string_view Text) {
const auto First = Text.find_first_not_of(" \t\r\v\f");
if (First == std::string_view::npos) return {};
return Text.substr(First, Text.find_last_not_of(" \t\r\v\f") - First + 1);
}
}
PreprocessedSource cps::preprocess(std::istream &Input) {
PreprocessedSource Result;
std::unordered_set<std::string> Switches;
struct Conditional { bool ParentActive; int Line; };
std::vector<Conditional> Conditions;
bool Active = true;
int LineNumber = 0;
auto Error = [&](const char *Message) {
sourceError(LineNumber, "%s", Message);
Result.HadError = true;
};
std::string Line;
while (std::getline(Input, Line)) {
++LineNumber;
Result.LibraryLines.push_back(Switches.count("__LIB") != 0);
auto Code = trim(Line);
size_t WordEnd = 0;
while (WordEnd < Code.size() && nameContinue(Code[WordEnd])) ++WordEnd;
auto Word = Code.substr(0, WordEnd);
bool Define = Word == "PP_DEFINE", Undef = Word == "PP_UNDEF";
bool Ifdef = Word == "PP_IFDEF", Ifndef = Word == "PP_IFNDEF";
bool Endif = Word == "PP_ENDIF";
bool Directive = Define || Undef || Ifdef || Ifndef || Endif;
bool Mask = Directive || !Active;
if (Directive) {
auto Tail = Code.substr(WordEnd);
Tail = trim(Tail.substr(0, Tail.find("//")));
if (Endif) {
if (!Tail.empty()) Error("PP_ENDIF does not take arguments");
if (Conditions.empty()) Error("PP_ENDIF without matching PP_IFDEF or PP_IFNDEF");
else {
Active = Conditions.back().ParentActive;
Conditions.pop_back();
}
} else if (Ifdef || Ifndef || Active) {
size_t NameEnd = 0;
if (!Tail.empty() && nameStart(Tail[0])) {
NameEnd = 1;
while (NameEnd < Tail.size() && nameContinue(Tail[NameEnd])) ++NameEnd;
}
bool Valid = NameEnd != 0 && NameEnd == Tail.size();
if (!Valid) {
sourceError(LineNumber, "%.*s requires exactly one switch name",
static_cast<int>(Word.size()), Word.data());
Result.HadError = true;
}
std::string Name(Tail.substr(0, NameEnd));
if (Ifdef || Ifndef) {
Conditions.push_back({Active, LineNumber});
bool Defined = Switches.count(Name) != 0;
Active = Active && Valid && (Ifdef ? Defined : !Defined);
} else if (Valid) {
if (Define) Switches.insert(Name);
else Switches.erase(Name);
}
}
}
if (Mask)
for (char &C : Line)
if (C != '\r') C = ' ';
Result.Text += Line;
if (!Input.eof()) Result.Text += '\n';
}
for (const auto &Condition : Conditions) {
sourceError(Condition.Line, "Unterminated preprocessor conditional: expected PP_ENDIF");
Result.HadError = true;
}
return Result;
}
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