All Questions
Tagged with compiler-construction lexical-analysis
149 questions
0
votes
1
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73
views
Parse an expression with non whitespace seperated operators
I am currently working on a compiler. Recently, I stumbled upon an issue concerning the parsing of operators in an expression. Obviously I have not found this to be an issue in other languages, which ...
- 11
1
vote
1
answer
366
views
Creating a static unordered_set from keys of a static unordered_map
I'm writing a front-end for a compiler and currently working on implementing punctuator scanning functionality. I've got a Punctuator class that I'd like to use to represent punctuators from the input ...
- 145
1
vote
0
answers
27
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Issue with identifying invalid lexemes in C initialization statement
I have been working on a code snippet to identify invalid lexemes in a C initialization statement. The code is intended to check for invalid data types, invalid identifiers, and invalid constant ...
- 11
0
votes
1
answer
32
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Typing /0 (not \0) into a lex program causes unexpected behavior
I made a simple lex program for school, and for some reason it has an unexpected behavior while reading "/0".
The program is as following:
%%
[a-z] printf("char %c", yytext[0]-32);
...
- 1
0
votes
1
answer
29
views
lex file not executing
I was tring to doing my assignment. That is "Write a program using YACC specifications to implement syntax analysis phase of compiler to validate type and syntax of variable declaration in C ...
1
vote
1
answer
396
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Binary and unary minus operator in Lexical Analyzer
So, I am doing a lexical analysis of a TOY programming language using flex. I am currently stuck at the following point.
Minus sign: As we know the minus sign can have two meanings by defining them as ...
- 109
-1
votes
1
answer
106
views
Avoiding overlap with similar regex patterns during tokenization
Background
I've made a couple simple compilers before, but I've never properly addressed this issue:
Say I have a token LT which searches the expression < and a token LTEQ which searches <=.
A ...
- 584
0
votes
0
answers
399
views
Lex program output is not coming
%{
int count=0;
%}
%%
[/][/][a-zA-Z0-9]* {count++;}
%%
int yywrap()
{
return 1;
}
int main()
{
yylex();
printf("lines: %d",count);
return 0;
}
I am executing this ...
0
votes
0
answers
94
views
Unexpected character JFLEX
Hello i was watching a tutorial on youtube. It was the start of tutorial but when i tried to wrote the code and run this flex.l file. The output show unexpected character [a-z] {printf("Single ...
- 1
2
votes
1
answer
176
views
Lex file doesn't recognize keywords. How can I write my regex to read particular keywords?
This is my lex file
%{
#include<stdio.h>
int codelines = 0;
int commentlines = 0;
int blanklines = 0;
int headerlines = 0;
int brackets = 0;
int keywords = 0;
%...
- 71
0
votes
2
answers
1k
views
How can i ignore comments in a string based on compiler design?
I want to ignore every comment like { comments } and // comments.
I have a pointer named peek that checks my string character by character. I know how to ignore newlines, tabs, and spaces but I don'...
0
votes
0
answers
74
views
How to determine the goal symbol when tokenize ECMAScript in lexical grammar
I'm writing a JS macro preprocessor, and refer to the ECMA-262 specification for some guide to parse js code.
I use the code parser to determine where to do macro replace in a standard/precise way, ...
- 13
1
vote
1
answer
1k
views
Parser gives a unknown type name error for entry_t
I'm editing my first parser and I'm very new to compiler design. I'm using a hashtable to store tokens. I have created a struct called struct_t in my symboletable.h file.
When I try to create a new ...
0
votes
1
answer
615
views
Lexical analyzer gives undefined error for yylineno
Im pretty new to compiler design. im trying to take the first step in lexical analyzer trying to run the following code.
%{
#include <stdlib.h>
#include <stdio.h>
#include "...
- 143
2
votes
1
answer
441
views
Skipping nested comments recursively in a scanner
I'm writing a scanner for a compiler and have a function to skip comments whenever it sees them, I wanted to know how one would skip nested comments, i.e something like " hello "w" ...
- 146