550696d49
Denys Vlasenko
2023-06-16
Subject
shell/math: tweka comments
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shell/math.c+8 -16
| @@ -46,7 +46,6 @@ | |
| * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE | |
| * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
| */ | |
| - | |
| /* This is my infix parser/evaluator. It is optimized for size, intended | |
| * as a replacement for yacc-based parsers. However, it may well be faster | |
| * than a comparable parser written in yacc. The supported operators are | |
| @@ -61,7 +60,6 @@ | |
| * to the stack instead of adding them to a queue to end up with an | |
| * expression). | |
| */ | |
| - | |
| /* | |
| * Aug 24, 2001 Manuel Novoa III | |
| * | |
| @@ -245,7 +243,6 @@ is_right_associative(operator prec) | |
| || prec == PREC(TOK_CONDITIONAL); | |
| } | |
| - | |
| typedef struct { | |
| arith_t val; | |
| char *var_name; | |
| @@ -254,13 +251,11 @@ typedef struct { | |
| #define VALID_NAME(name) (name) | |
| #define NOT_NAME(name) (!(name)) | |
| - | |
| typedef struct remembered_name { | |
| struct remembered_name *next; | |
| const char *var_name; | |
| } remembered_name; | |
| - | |
| static arith_t | |
| evaluate_string(arith_state_t *math_state, const char *expr); | |
| @@ -278,7 +273,7 @@ arith_lookup_val(arith_state_t *math_state, var_or_num_t *t) | |
| */ | |
| for (cur = math_state->list_of_recursed_names; cur; cur = cur->next) { | |
| if (strcmp(cur->var_name, t->var_name) == 0) { | |
| - | /* Yes */ |
| + | /* yes */ |
| return "expression recursion loop detected"; | |
| } | |
| } | |
| @@ -500,7 +495,6 @@ static const char op_tokens[] ALIGN1 = { | |
| '+', 0, TOK_ADD, | |
| '-', 0, TOK_SUB, | |
| '^', 0, TOK_BXOR, | |
| - | /* uniq */ |
| '~', 0, TOK_BNOT, | |
| ',', 0, TOK_COMMA, | |
| '?', 0, TOK_CONDITIONAL, | |
| @@ -869,14 +863,9 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| if (errmsg) | |
| goto err_with_custom_msg; | |
| dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[-1].val, numstackptr[-1].var_name); | |
| - | /* For ternary ?: we need to remove ? from opstack too, not just : */ |
| if (prev_op == TOK_CONDITIONAL_SEP) { | |
| - | // This is caught in arith_apply() |
| - | //if (opstackptr == opstack) { |
| - | // /* Example: $((2:3)) */ |
| - | // errmsg = "where is your ? in ?:"; |
| - | // goto err_with_custom_msg; |
| - | //} |
| + | /* We just executed ":" */ |
| + | /* Remove "?" from opstack too, not just ":" */ |
| opstackptr--; | |
| if (*opstackptr != TOK_CONDITIONAL) { | |
| /* Example: $((1,2:3)) */ | |
| @@ -890,12 +879,14 @@ dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[ | |
| dbg("':' executed: evaluation_disabled=%llx (restored)", EVAL_DISABLED); | |
| } | |
| } /* while (opstack not empty) */ | |
| + | |
| if (op == TOK_RPAREN) /* unpaired RPAREN? */ | |
| goto err; | |
| check_cond: | |
| if (op == TOK_CONDITIONAL) { | |
| - | /* We know the value of EXPR in "EXPR ? ..." |
| - | * Should we stop evaluating now? */ |
| + | /* We just now evaluated EXPR before "?". |
| + | * Should we disable evaluation now? |
| + | */ |
| if (math_state->evaluation_disabled & TOP_BIT_ULL) | |
| goto err; /* >63 levels of ?: nesting not supported */ | |
| math_state->evaluation_disabled <<= 1; | |
| @@ -915,6 +906,7 @@ dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[ | |
| insert_op = 0xff; | |
| dbg("inserting %02x", op); | |
| if (op == TOK_CONDITIONAL_SEP) { | |
| + | /* The next token is ":". Toggle "do not evaluate" bit */ |
| math_state->evaluation_disabled ^= 1; | |
| dbg("':' entered: evaluation_disabled=%llx (negated)", EVAL_DISABLED); | |
| } | |