Nasal-Interpreter/test/lexer.nas

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import("lib.nas");
var lexer=func(file)
{
var (ptr,token)=(0,[]);
var s=io.fin(file);
var len=size(s);
return
{
jmp_note:func()
{
while(ptr<len and chr(s[ptr])!='\n')
ptr+=1;
ptr+=1;
},
id_gen:func()
{
var tmp="";
while(ptr<len)
{
var c=s[ptr];
if(('a'[0]<=c and c<='z'[0])
or ('A'[0]<=c and c<='Z'[0])
or ('0'[0]<=c and c<='9'[0])
or c=='_'[0])
tmp~=chr(c);
else
break;
ptr+=1;
}
append(token,tmp);
},
str_gen:func()
{
var str="";
var mark=chr(s[ptr]);
ptr+=1;
while(ptr<len and chr(s[ptr])!=mark)
{
if(chr(s[ptr])=='\\')
{
ptr+=1;
var c=chr(s[ptr]);
if (c=='a' ) str~='\a';
elsif(c=='b' ) str~='\b';
elsif(c=='f' ) str~='\f';
elsif(c=='n' ) str~='\n';
elsif(c=='r' ) str~='\r';
elsif(c=='t' ) str~='\t';
elsif(c=='v' ) str~='\v';
elsif(c=='?' ) str~='\?';
elsif(c=='0' ) str~='\0';
elsif(c=='\\') str~='\\';
elsif(c=='\'') str~='\'';
elsif(c=='\"') str~='\"';
else str~=c;
}
else
str~=chr(s[ptr]);
ptr+=1;
}
if(ptr>=len)
print("read eof when generating string.\n");
ptr+=1;
append(token,str);
},
num_gen:func()
{
var number=chr(s[ptr]);
ptr+=1;
if(ptr<len and chr(s[ptr])=='x')
{
ptr+=1;
while(ptr<len and
('a'[0]<=s[ptr] and s[ptr]<='f'[0]
or '0'[0]<=s[ptr] and s[ptr]<='9'[0]))
{
number~=chr(s[ptr]);
ptr+=1;
}
append(token,num(number));
return;
}
elsif(ptr<len and chr(s[ptr])=='o')
{
ptr+=1;
while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='7'[0]))
{
number~=chr(s[ptr]);
ptr+=1;
}
append(token,num(number));
return;
}
while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0]))
{
number~=chr(s[ptr]);
ptr+=1;
}
if(ptr<len and chr(s[ptr])=='.')
{
number~=chr(s[ptr]);
ptr+=1;
while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0]))
{
number~=chr(s[ptr]);
ptr+=1;
}
}
if(chr(s[ptr])=='e' or chr(s[ptr])=='E')
{
number~=chr(s[ptr]);
ptr+=1;
if(chr(s[ptr])=='-' or chr(s[ptr])=='+')
{
number~=chr(s[ptr]);
ptr+=1;
}
while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0]))
{
number~=chr(s[ptr]);
ptr+=1;
}
}
var last_c=chr(number[-1]);
if(last_c=='.' or last_c=='e' or last_c=='E' or last_c=='-' or last_c=='+')
println("error number: ",number);
append(token,num(number));
},
opr_gen:func()
{
var c=chr(s[ptr]);
if(c=='+' or c=='-' or c=='~' or c=='/' or c=='*' or c=='>' or c=='<' or c=='!' or c=='=')
{
var tmp=c;
ptr+=1;
if(ptr<len and chr(s[ptr])=='=')
{
tmp~=chr(s[ptr]);
ptr+=1;
}
append(token,tmp);
return;
}
elsif(c=='.')
{
if(ptr+2<len and chr(s[ptr+1])=='.' and chr(s[ptr+2])=='.')
{
append(token,"...");
ptr+=3;
}
else
{
append(token,".");
ptr+=1;
}
return;
}
elsif(c!=' ' and c!='\t' and c!='\n' and c!='\r' and s[ptr]>0)
append(token,c);
ptr+=1;
return;
},
compile:func()
{
while(ptr<len)
{
var c=s[ptr];
if(c=='#'[0])
me.jmp_note();
elsif('a'[0]<=c and c<='z'[0]
or 'A'[0]<=c and c<='Z'[0]
or c=='_'[0])
me.id_gen();
elsif(c=='\''[0] or c=='\"'[0])
me.str_gen();
elsif('0'[0]<=c and c<='9'[0])
me.num_gen();
else
me.opr_gen();
}
return;
},
get_token:func(){return token;}
};
}
var lex=lexer("test/props.nas");
lex.compile();
foreach(var tok;lex.get_token())
print(tok,' ');
print('\n');