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* An attribute set update operator (//). E.g.,

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{x=1; y=2; z=3;} // {y=4;}  =>  {x=1; y=4; z=3;}
This commit is contained in:
Eelco Dolstra 2004-02-04 16:49:51 +00:00
parent 6d46e647ba
commit 9d25466b34
3 changed files with 19 additions and 0 deletions
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16
src/libexpr/eval.cc
View file

@ -134,6 +134,18 @@ ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds)
}
static Expr updateAttrs(Expr e1, Expr e2)
{
/* Note: e1 and e2 should be in normal form. */
ATermMap attrs;
queryAllAttrs(e1, attrs);
queryAllAttrs(e2, attrs);
return makeAttrs(attrs);
}
string evalString(EvalState & state, Expr e)
{
e = evalExpr(state, e);
@ -264,6 +276,10 @@ Expr evalExpr2(EvalState & state, Expr e)
if (atMatch(m, e) >> "OpOr" >> e1 >> e2)
return makeBool(evalBool(state, e1) || evalBool(state, e2));
/* Attribut set update (//). */
if (atMatch(m, e) >> "OpUpdate" >> e1 >> e2)
return updateAttrs(evalExpr(state, e1), evalExpr(state, e2));
/* Barf. */
throw badTerm("invalid expression", e);
}

1
src/libexpr/lexer.l
View file

@ -57,6 +57,7 @@ inherit { return INHERIT; }
\&\& { return AND; }
\|\| { return OR; }
\-\> { return IMPL; }
\/\/ { return UPDATE; }
{ID} { yylval->t = ATmake("<str>", yytext); return ID; /* !!! alloc */ }
{INT} { int n = atoi(yytext); /* !!! overflow */

2
src/libexpr/parser.y
View file

@ -42,6 +42,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, void * data, char * s)
%left OR
%left AND
%nonassoc EQ NEQ
%right UPDATE
%left NEG
%%
@ -69,6 +70,7 @@ expr_op
| expr_op AND expr_op { $$ = ATmake("OpAnd(<term>, <term>)", $1, $3); }
| expr_op OR expr_op { $$ = ATmake("OpOr(<term>, <term>)", $1, $3); }
| expr_op IMPL expr_op { $$ = ATmake("OpImpl(<term>, <term>)", $1, $3); }
| expr_op UPDATE expr_op { $$ = ATmake("OpUpdate(<term>, <term>)", $1, $3); }
| expr_app
;