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#include <stdexcept>
#include <cstring>
#include <cctype>
#include <cassert>
#include "parser.h"
using namespace std;
ParseError::ParseError(const string &what_arg)
:runtime_error(what_arg){}
ParseError::ParseError(const char *what_arg)
:runtime_error(what_arg){}
static bool isinitwordchar(char c){
return isalpha(c)||c=='_';
}
static bool iswordchar(char c){
return isalpha(c)||isdigit(c)||c=='_';
}
static const vector<string> tok_symbols={
"==", "!=", ">", "<", ">=", "<=",
":=", "=",
"+", "-", "*", "/", "%",
"(", ")", ",",
"{", "}", "?{", "??{", "}&",
};
static bool isSymbolPrefix(const string &s){
for(const string &sym : tok_symbols){
if(s.size()<=sym.size()&&sym.substr(0,s.size())==s)return true;
}
return false;
}
template <typename T>
static bool contains(const vector<T> &v,const T &target){
for(const T &t : v){
if(t==target)return true;
}
return false;
}
class Token{
public:
enum class Type{
word,
number,
string,
symbol,
};
Type type;
string str;
Site site;
Token(Type type,const string &str,const Site &site)
:type(type),str(str),site(site){}
};
class Tokeniser{
const string &source;
const string &filename;
i64 idx,nextidx;
i64 lnum,linex;
Token::Type ttype;
bool eof(i64 at){
return at>=(i64)source.size();
}
string get_() const {
if(eof())throw runtime_error("Tokeniser::get() on eof");
if(nextidx==-1)throw runtime_error("Tokeniser::get() before advance");
if(nextidx==-2)throw runtime_error("Tokeniser::get() after eof");
assert(nextidx>=0);
return source.substr(idx,nextidx-idx);
}
public:
Tokeniser(const string &source,const string &filename)
:source(source),filename(filename),
idx(0),nextidx(-1),
lnum(1),linex(1){}
bool eof() const {
return idx>=(i64)source.size();
}
Token get() const {
return Token(ttype,get_(),Site(filename,lnum,linex));
}
// Returns whether there are more tokens
bool advance(){
if(eof())return false;
while(idx<nextidx){
if(source[idx]=='\n'){
lnum++;
linex=1;
} else {
linex++;
}
idx++;
}
while(true){
i64 origidx=idx;
while(!eof()&&isspace(source[idx])){
if(source[idx]=='\n'){
lnum++;
linex=1;
} else {
linex++;
}
idx++;
}
if(eof())return false;
if(source[idx]=='#'){
while(!eof()&&source[idx]!='\n')idx++;
idx++;
lnum++;
linex=1;
if(eof())return false;
}
if(idx==origidx)break;
}
nextidx=idx;
// Word
if(isinitwordchar(source[nextidx])){
ttype=Token::Type::word;
do nextidx++;
while(!eof(nextidx)&&iswordchar(source[nextidx]));
return true;
}
// Number literal
if(isdigit(source[nextidx])||(!eof(nextidx+1)&&source[nextidx]=='-'&&isdigit(source[nextidx+1]))){
ttype=Token::Type::number;
if(source[nextidx]=='-')nextidx++;
while(!eof(nextidx)&&isdigit(source[nextidx]))nextidx++;
if(eof(nextidx))return true;
if(source[nextidx]=='.'){
nextidx++;
if(eof(nextidx)||!isdigit(source[nextidx])){
throw ParseError("Incomplete floating point literal at EOF");
}
while(!eof(nextidx)&&isdigit(source[nextidx]))nextidx++;
if(eof(nextidx))return true;
}
if(strchr("eE",source[nextidx])!=NULL){
nextidx++;
if(eof(nextidx)||strchr("+-0123456789",source[nextidx])==NULL){
throw ParseError("Incomplete floating point literal at EOF");
}
if(strchr("+-",source[nextidx])!=NULL){
nextidx++;
if(eof(nextidx))throw ParseError("Incomplete floating point literal at EOF");
}
while(!eof(nextidx)&&isdigit(source[nextidx]))nextidx++;
}
return true;
}
// String literal
if(source[nextidx]=='"'){
ttype=Token::Type::string;
nextidx++;
while(!eof(nextidx)&&source[nextidx]!='"'){
if(source[nextidx]=='\\')nextidx++;
}
if(eof(nextidx))throw ParseError("Incomplete string literal at EOF");
nextidx++;
return true;
}
// Symbol
if(isSymbolPrefix({source[idx]})){
ttype=Token::Type::symbol;
nextidx++;
while(!eof(nextidx)){
if(!isSymbolPrefix(get_()))return true;
nextidx++;
}
if(contains(tok_symbols,get_()))return true;
else throw ParseError("Unknown symbol at EOF");
}
throw ParseError("Unknown token starting at '"+source.substr(idx,5)+"'");
}
};
StatementList parse(const string &source,const string &filename){
Tokeniser tokeniser(source,filename);
StatementList stl;
while(tokeniser.advance()){
Token tok=tokeniser.get();
}
return stl;
}
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