lix/src/libexpr/lexer.l
Eelco Dolstra 37d7abd694 * New language feature: with expressions.
The expression `with E1; E2' evaluates to E2 with all bindings in
  the attribute set E1 substituted.  E.g.,

    with {x = 123;}; x

  evaluates to 123.  That is, the attribute set E1 is in scope in E2.

  This is particularly useful when importing files containing lots
  definitions.  E.g., instead of

    let {
      inherit (import ./foo.nix) a b c d e f;

      body = ... a ... f ...;
    }

  we can now say

    with import ./foo.nix;

    ... a ... f ...

  I.e., we don't have to say what variables should be brought into scope.
2004-10-25 16:54:56 +00:00

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%option reentrant bison-bridge bison-locations
%option noyywrap
%option never-interactive
%{
#include <string.h>
#include <aterm2.h>
#include "parser-tab.h"
static void initLoc(YYLTYPE * loc)
{
loc->first_line = 1;
loc->first_column = 1;
}
static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
{
while (len--) {
switch (*s++) {
case '\n':
++loc->first_line;
loc->first_column = 1;
break;
default:
++loc->first_column;
}
}
}
#define YY_USER_INIT initLoc(yylloc)
#define YY_USER_ACTION adjustLoc(yylloc, yytext, yyleng);
%}
ID [a-zA-Z\_][a-zA-Z0-9\_\']*
INT [0-9]+
STR \"[^\n\"]*\"
PATH [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+
URI [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
%%
if { return IF; }
then { return THEN; }
else { return ELSE; }
assert { return ASSERT; }
with { return WITH; }
let { return LET; }
rec { return REC; }
inherit { return INHERIT; }
\=\= { return EQ; }
\!\= { return NEQ; }
\&\& { return AND; }
\|\| { return OR; }
\-\> { return IMPL; }
\/\/ { return UPDATE; }
{ID} { yylval->t = ATmake("<str>", yytext); return ID; /* !!! alloc */ }
{INT} { int n = atoi(yytext); /* !!! overflow */
yylval->t = ATmake("<int>", n);
return INT;
}
{STR} { int len = strlen(yytext);
yytext[len - 1] = 0;
yylval->t = ATmake("<str>", yytext + 1);
yytext[len - 1] = '\"';
return STR; /* !!! alloc */
}
{PATH} { yylval->t = ATmake("<str>", yytext); return PATH; /* !!! alloc */ }
{URI} { yylval->t = ATmake("<str>", yytext); return URI; /* !!! alloc */ }
[ \t\n]+ /* eat up whitespace */
\#[^\n]* /* single-line comments */
\/\*(.|\n)*\*\/ /* long comments */
. return yytext[0];
%%