diff options
| -rw-r--r-- | toys/pending/expr.c | 33 |
1 files changed, 17 insertions, 16 deletions
diff --git a/toys/pending/expr.c b/toys/pending/expr.c index ca0507ef..e1068312 100644 --- a/toys/pending/expr.c +++ b/toys/pending/expr.c @@ -57,7 +57,7 @@ config EXPR #include "toys.h" GLOBALS( - char *tok; // current token, not on the stack since recursive calls mutate it + char **tok; // current token, not on the stack since recursive calls mutate it ) // Scalar value. If s != NULL, it's a string, otherwise it's an int. @@ -210,31 +210,31 @@ void eval_op(struct op_def *o, struct value *ret, struct value *rhs) // algorithm, setting 'ret'. static void eval_expr(struct value *ret, int min_prec) { - if (!TT.tok) error_exit("Unexpected end of input"); + if (!*TT.tok) error_exit("Unexpected end of input"); // Evaluate LHS atom, setting 'ret'. - if (!strcmp(TT.tok, "(")) { // parenthesized expression - TT.tok = *toys.optargs++; // consume ( + if (!strcmp(*TT.tok, "(")) { // parenthesized expression + TT.tok++; // consume ( + eval_expr(ret, 1); // We're inside ( ), so min_prec = 1 - if (!TT.tok) error_exit("Expected )"); // TODO: Also says that for () - if (strcmp(TT.tok, ")")) error_exit("Expected ) but got %s", TT.tok); - TT.tok = *toys.optargs++; // consume ) - } else { // simple literal - ret->s = TT.tok; // all values start as strings - TT.tok = *toys.optargs++; - } + if (ret->s && !strcmp(ret->s, ")")) error_exit("empty ( )"); + if (!*TT.tok) error_exit("Expected )"); + if (strcmp(*TT.tok, ")")) error_exit("Expected ) but got %s", *TT.tok); + } else ret->s = *TT.tok; // simple literal, all values start as strings + TT.tok++; // Evaluate RHS and apply operator until precedence is too low. struct value rhs; - while (TT.tok) { + while (*TT.tok) { struct op_def *o = OPS; + while (o->tok) { // Look up operator - if (!strcmp(TT.tok, o->tok)) break; + if (!strcmp(*TT.tok, o->tok)) break; o++; } if (!o->tok) break; // Not an operator (extra input will fail later) if (o->prec < min_prec) break; // Precedence too low, pop a stack frame - TT.tok = *toys.optargs++; + TT.tok++; eval_expr(&rhs, o->prec + 1); // Evaluate RHS, with higher min precedence eval_op(o, ret, &rhs); // Apply operator, setting 'ret' @@ -244,10 +244,11 @@ static void eval_expr(struct value *ret, int min_prec) void expr_main(void) { struct value ret = {0}; + toys.exitval = 2; // if exiting early, indicate error - TT.tok = *toys.optargs++; // initialize global token + TT.tok = toys.optargs; // initialize global token eval_expr(&ret, 1); - if (TT.tok) error_exit("Unexpected extra input '%s'\n", TT.tok); + if (*TT.tok) error_exit("Unexpected extra input '%s'\n", *TT.tok); if (ret.s) printf("%s\n", ret.s); else printf("%lld\n", ret.i); |