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#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <unordered_map>
#include <stack>
#include <functional>
#include <cstdlib>
#include <cstring>
using namespace std;
inline bool isword(char c){return isalpha(c)||c=='_'||c=='@'||c=='$';}
inline bool isextword(char c){return isword(c)||isdigit(c);}
inline bool isoperator(char c){return (bool)strchr("+-*/=><!%^?{}",c);}
vector<string> tokenise(istream &stream){
vector<string> tokens;
string token;
char c,stringmode;
while(true){
c=stream.get();
if(!stream)break;
if(isword(c)||(token.size()>0&&isextword(c))){
token+=c;
} else if(isdigit(c)){
if(token.size()==0)token="#";
token+=c;
} else {
if(token.size())tokens.push_back(move(token));
else if(isoperator(c))tokens.push_back(string(1,c));
else if(c=='"'||c=='\''){
stringmode=c;
while(true){
c=stream.get();
if(!stream)throw string("Non-terminated string at end of file");
if(c==stringmode){
token="'"+token;
tokens.push_back(move(token));
break;
}
if(c=='\\'){
c=stream.get();
if(!stream)throw string("Non-terminated escape sequence in string at end of file");
switch(c){
case 'n':c='\n';break;
case 'r':c='\r';break;
case 't':c='\t';break;
case '0':c='\0';break;
case 'x':{
int res;
c=stream.get();
cerr<<"Parsed "<<c;
if(!stream)throw string("Non-terminated hexadecimal escape sequence in string at end of file");
res=c>='0'&&c<='9'?c-'0':(c>='a'&&c<='f')||(c>='A'&&c<='F')?(c&~32)-'A'+10:-1;
if(res==-1)throw "Invalid character '"+string(1,c)+"'' in hexadecimal escape sequence in string";
res*=16;
c=stream.get();
cerr<<c<<" into ";
if(!stream)throw string("Non-terminated hexadecimal escape sequence in string at end of file");
res+=c>='0'&&c<='9'?c-'0':(c>='a'&&c<='f')||(c>='A'&&c<='F')?(c&~32)-'A'+10:-241;
if(res<0)throw "Invalid character '"+string(1,c)+"'' in hexadecimal escape sequence in string";
c=(char)res;
cerr<<(int)c<<endl;
break;
}
}
}
token+=c;
}
} else if(isspace(c));
else throw string("Invalid character found in source: '")+c+'\'';
}
}
return tokens;
}
string readfile(ifstream stream){
stream.seekg(0,ios::end);
size_t len=stream.tellg();
stream.seekg(0,ios::beg);
string contents;
contents.resize(len);
stream.read(&*contents.begin(),len);
return contents;
}
struct Stackitem{
bool isstr;
string strval;
int intval;
};
const unordered_map<string,function<void(stack<Stackitem>&,unordered_map<string,Stackitem>&)>> builtins={
{"+",[](stack<Stackitem> &S,unordered_map<string,Stackitem> &variables){
if(S.size()<2)throw string("Builtin '+' needs 2 stack items");
Stackitem a,b,c;
b=S.top(); S.pop();
a=S.top(); S.pop();
if(!a.isstr&&!b.isstr){
S.push({false,"",a.intval+b.intval});
return;
}
if(!a.isstr){
a.strval=to_string(a.intval);
a.isstr=true;
}
if(!b.isstr){
b.strval=to_string(b.intval);
b.isstr=true;
}
S.push({true,a.strval+b.strval,0});
}},
{"-",[](stack<Stackitem> &S,unordered_map<string,Stackitem> &variables){
if(S.size()<2)throw string("Builtin '-' needs 2 stack items");
Stackitem a,b,c;
b=S.top(); S.pop();
a=S.top(); S.pop();
if(a.isstr||b.isstr)throw string("Builtin '-' cannot accept a string argument");
S.push({false,"",a.intval-b.intval});
}},
{"print",[](stack<Stackitem> &S,unordered_map<string,Stackitem> &variables){
if(S.size()<1)throw string("Builtin 'print' needs 1 stack item");
Stackitem v;
v=S.top(); S.pop();
if(v.isstr)cout<<v.strval<<flush;
else cout<<v.intval<<flush;
}}
};
void runpass2(const vector<string> &T,
stack<Stackitem> &S,
const unordered_map<string,vector<string>> &functions,
unordered_map<string,Stackitem> &variables){
unsigned int cursor;
for(cursor=0;cursor<T.size();cursor++){
const string &word=T[cursor];
//cerr<<"Executing word <"<<word<<'>'<<endl;
if(word[0]=='#'){
S.push({false,"",(int)strtol(word.data()+1,NULL,10)});
} else if(word[0]=='\''){
S.push({true,word.substr(1),0});
} else {
auto it=variables.find(word);
if(it!=variables.end()){
S.push(it->second);
} else {
auto it=functions.find(word);
if(it!=functions.end()){
runpass2(it->second,S,functions,variables);
} else {
auto it=builtins.find(word);
if(it==builtins.end())throw "Unknown variable or function '"+word+"'";
it->second(S,variables);
}
}
}
}
}
void run(vector<string> T){
unordered_map<string,vector<string>> functions;
unordered_map<string,Stackitem> variables;
stack<Stackitem> S;
unsigned int cursor=0;
//first pass, handle functions and includes
while(cursor<T.size()){
const string &word=T[cursor];
if(word=="@defun"){
if(cursor+3>=T.size())throw string("Unterminated @defun statement at end of file");
string name=T[cursor+1];
if(name[0]!='\'')throw string("@defun expected a string as name, but got '")+name+"'";
name.erase(0,1);
if(T[cursor+2]!="{")throw string("Invalid @defun statement of function ")+name;
unsigned int start=cursor+3;
unsigned int end;
for(end=start;end<T.size()&&T[end]!="}";end++);
vector<string> &functoks=functions[name];
functoks.resize(end-start);
for(unsigned int i=start;i<end;i++)functoks[i]=move(T[i]);
T.erase(T.begin()+cursor,T.begin()+end+1);
} else if(word=="@include"){
if(cursor+1>=T.size())throw string("Unterminated @include statement at end of file");
string name=T[cursor+1];
if(name[0]!='\'')throw string("@include expected a string as file, but got '")+name+"'";
name.erase(0,1);
ifstream file(name);
if(!file)throw string("Could not open file '")+name+"' specified by @include statement";
vector<string> included=tokenise(file);
file.close();
T.erase(T.begin()+cursor,T.begin()+cursor+2);
T.insert(T.begin()+cursor,included.begin(),included.end());
} else {
cursor++;
}
}
//second pass, evaluate file
runpass2(T,S,functions,variables);
}
int main(int argc,char **argv){
if(argc!=2){
cerr<<"Call this interpreter with the Postrun source file"<<endl;
return 1;
}
ifstream srcf(argv[1]);
if(!srcf){
cerr<<"Could not open file '"<<argv[1]<<"'"<<endl;
return 1;
}
//string source=readfile(srcf);
try {
const vector<string> tokens=tokenise(srcf);
for(const string &tok : tokens)cerr<<'['<<tok<<"] "; cerr<<endl;
run(tokens);
srcf.close();
} catch(string e){
cerr<<"ERROR: "<<e<<endl;
return 1;
}
}
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