tvl-depot/src/libexpr/lexer.l
Guillaume Maudoux a143014d73 lexer: remove catch-all rules hiding real errors
With catch-all rules, we hide potential errors.
It turns out that a4744254 made one cath-all useless. Flex detected that
is was impossible to reach.
The other is more subtle, as it can only trigger on unfinished escapes
in unfinished strings, which only occurs at EOF.
2017-05-01 01:18:06 +02:00

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%option reentrant bison-bridge bison-locations
%option noyywrap
%option never-interactive
%option stack
%option nodefault
%option nounput noyy_top_state
%x STRING
%x IND_STRING
%x INSIDE_DOLLAR_CURLY
%{
#include "nixexpr.hh"
#include "parser-tab.hh"
using namespace nix;
namespace nix {
static void initLoc(YYLTYPE * loc)
{
loc->first_line = loc->last_line = 1;
loc->first_column = loc->last_column = 1;
}
static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
{
loc->first_line = loc->last_line;
loc->first_column = loc->last_column;
while (len--) {
switch (*s++) {
case '\r':
if (*s == '\n') /* cr/lf */
s++;
/* fall through */
case '\n':
++loc->last_line;
loc->last_column = 1;
break;
default:
++loc->last_column;
}
}
}
static Expr * unescapeStr(SymbolTable & symbols, const char * s)
{
string t;
char c;
while ((c = *s++)) {
if (c == '\\') {
assert(*s);
c = *s++;
if (c == 'n') t += '\n';
else if (c == 'r') t += '\r';
else if (c == 't') t += '\t';
else t += c;
}
else if (c == '\r') {
/* Normalise CR and CR/LF into LF. */
t += '\n';
if (*s == '\n') s++; /* cr/lf */
}
else t += c;
}
return new ExprString(symbols.create(t));
}
}
#define YY_USER_INIT initLoc(yylloc)
#define YY_USER_ACTION adjustLoc(yylloc, yytext, yyleng);
#define PUSH_STATE(state) yy_push_state(state, yyscanner)
#define POP_STATE() yy_pop_state(yyscanner)
%}
ID [a-zA-Z\_][a-zA-Z0-9\_\'\-]*
INT [0-9]+
FLOAT (([1-9][0-9]*\.[0-9]*)|(0?\.[0-9]+))([Ee][+-]?[0-9]+)?
PATH [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
HPATH \~(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
SPATH \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>
URI [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
%%
<INITIAL,INSIDE_DOLLAR_CURLY>{
if { return IF; }
then { return THEN; }
else { return ELSE; }
assert { return ASSERT; }
with { return WITH; }
let { return LET; }
in { return IN; }
rec { return REC; }
inherit { return INHERIT; }
or { return OR_KW; }
\.\.\. { return ELLIPSIS; }
\=\= { return EQ; }
\!\= { return NEQ; }
\<\= { return LEQ; }
\>\= { return GEQ; }
\&\& { return AND; }
\|\| { return OR; }
\-\> { return IMPL; }
\/\/ { return UPDATE; }
\+\+ { return CONCAT; }
{ID} { yylval->id = strdup(yytext); return ID; }
{INT} { errno = 0;
yylval->n = strtol(yytext, 0, 10);
if (errno != 0)
throw ParseError(format("invalid integer %1%") % yytext);
return INT;
}
{FLOAT} { errno = 0;
yylval->nf = strtod(yytext, 0);
if (errno != 0)
throw ParseError(format("invalid float %1%") % yytext);
return FLOAT;
}
\$\{ { PUSH_STATE(INSIDE_DOLLAR_CURLY); return DOLLAR_CURLY; }
}
\} { return '}'; }
<INSIDE_DOLLAR_CURLY>\} { POP_STATE(); return '}'; }
\{ { return '{'; }
<INSIDE_DOLLAR_CURLY>\{ { PUSH_STATE(INSIDE_DOLLAR_CURLY); return '{'; }
<INITIAL,INSIDE_DOLLAR_CURLY>\" {
PUSH_STATE(STRING); return '"';
}
<STRING>([^\$\"\\]|\$[^\{\"\\]|\\.|\$\\.)*\$/\" |
<STRING>([^\$\"\\]|\$[^\{\"\\]|\\.|\$\\.)+ {
/* It is impossible to match strings ending with '$' with one
regex because trailing contexts are only valid at the end
of a rule. (A sane but undocumented limitation.) */
yylval->e = unescapeStr(data->symbols, yytext);
return STR;
}
<STRING>\$\{ { PUSH_STATE(INSIDE_DOLLAR_CURLY); return DOLLAR_CURLY; }
<STRING>\" { POP_STATE(); return '"'; }
<STRING>\$|\\|\$\\ {
/* This can only occur when we reach EOF, otherwise the above
(...|\$[^\{\"\\]|\\.|\$\\.)+ would have triggered.
This is technically invalid, but we leave the problem to the
parser who fails with exact location. */
return STR;
}
<INITIAL,INSIDE_DOLLAR_CURLY>\'\'(\ *\n)? { PUSH_STATE(IND_STRING); return IND_STRING_OPEN; }
<IND_STRING>([^\$\']|\$[^\{\']|\'[^\'\$])+ {
yylval->e = new ExprIndStr(yytext);
return IND_STR;
}
<IND_STRING>\'\'\$ |
<IND_STRING>\$ {
yylval->e = new ExprIndStr("$");
return IND_STR;
}
<IND_STRING>\'\'\' {
yylval->e = new ExprIndStr("''");
return IND_STR;
}
<IND_STRING>\'\'\\. {
yylval->e = unescapeStr(data->symbols, yytext + 2);
return IND_STR;
}
<IND_STRING>\$\{ { PUSH_STATE(INSIDE_DOLLAR_CURLY); return DOLLAR_CURLY; }
<IND_STRING>\'\' { POP_STATE(); return IND_STRING_CLOSE; }
<IND_STRING>\' {
yylval->e = new ExprIndStr("'");
return IND_STR;
}
<INITIAL,INSIDE_DOLLAR_CURLY>{
{PATH} { if (yytext[yyleng-1] == '/')
throw ParseError("path %s has a trailing slash", yytext);
yylval->path = strdup(yytext);
return PATH;
}
{HPATH} { if (yytext[yyleng-1] == '/')
throw ParseError("path %s has a trailing slash", yytext);
yylval->path = strdup(yytext);
return HPATH;
}
{SPATH} { yylval->path = strdup(yytext); return SPATH; }
{URI} { yylval->uri = strdup(yytext); return URI; }
[ \t\r\n]+ /* eat up whitespace */
\#[^\r\n]* /* single-line comments */
\/\*([^*]|\*+[^*/])*\*+\/ /* long comments */
. return yytext[0];
}
<<EOF>> { data->atEnd = true; return 0; }
%%