shell/math: deconvolute and explain ?: handling. Give better error message
function old new delta arith_apply 1271 1283 +12 Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko
parent
063847d6bd
commit
bed7c81ea2
@ -5516,7 +5516,7 @@ cvtnum(arith_t num)
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int len;
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expdest = makestrspace(32, expdest);
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len = fmtstr(expdest, 32, arith_t_fmt, num);
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len = fmtstr(expdest, 32, ARITH_FMT, num);
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STADJUST(len, expdest);
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return len;
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}
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@ -72,7 +72,7 @@ ghi
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./arith.tests: line 191: arithmetic syntax error
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16 16
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./arith.tests: line 196: arithmetic syntax error
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./arith.tests: line 197: arithmetic syntax error
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./arith.tests: line 197: malformed ?: operator
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./arith.tests: line 198: arithmetic syntax error
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9 9
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./arith.tests: line 205: arithmetic syntax error
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@ -4938,8 +4938,8 @@ static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg)
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*p = '\0'; /* replace trailing <SPECIAL_VAR_SYMBOL> */
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debug_printf_subst("ARITH '%s' first_ch %x\n", arg, first_ch);
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res = expand_and_evaluate_arith(arg, NULL);
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debug_printf_subst("ARITH RES '"arith_t_fmt"'\n", res);
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sprintf(arith_buf, arith_t_fmt, res);
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debug_printf_subst("ARITH RES '"ARITH_FMT"'\n", res);
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sprintf(arith_buf, ARITH_FMT, res);
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val = arith_buf;
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break;
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}
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@ -81,7 +81,7 @@ ghi
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hush: arithmetic syntax error
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16 16
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hush: arithmetic syntax error
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hush: arithmetic syntax error
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hush: malformed ?: operator
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hush: arithmetic syntax error
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9 9
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hush: arithmetic syntax error
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239
shell/math.c
239
shell/math.c
@ -1,5 +1,5 @@
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/*
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* arithmetic code ripped out of ash shell for code sharing
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* Arithmetic code ripped out of ash shell for code sharing.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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@ -154,7 +154,7 @@ typedef unsigned char operator;
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#define fix_assignment_prec(prec) do { if (prec == 3) prec = 2; } while (0)
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/* ternary conditional operator is right associative too */
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/* Ternary conditional operator is right associative too */
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#define TOK_CONDITIONAL tok_decl(4,0)
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#define TOK_CONDITIONAL_SEP tok_decl(4,1)
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@ -186,10 +186,10 @@ typedef unsigned char operator;
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#define TOK_DIV tok_decl(14,1)
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#define TOK_REM tok_decl(14,2)
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/* exponent is right associative */
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/* Exponent is right associative */
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#define TOK_EXPONENT tok_decl(15,1)
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/* unary operators */
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/* Unary operators */
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#define UNARYPREC 16
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#define TOK_BNOT tok_decl(UNARYPREC,0)
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#define TOK_NOT tok_decl(UNARYPREC,1)
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@ -213,30 +213,37 @@ typedef unsigned char operator;
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#define TOK_RPAREN tok_decl(SPEC_PREC, 1)
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static int
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tok_have_assign(operator op)
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is_assign_op(operator op)
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{
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operator prec = PREC(op);
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fix_assignment_prec(prec);
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return (prec == PREC(TOK_ASSIGN) ||
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prec == PREC_PRE || prec == PREC_POST);
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return prec == PREC(TOK_ASSIGN)
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|| prec == PREC_PRE
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|| prec == PREC_POST;
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}
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static int
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is_right_associative(operator prec)
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{
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return (prec == PREC(TOK_ASSIGN) || prec == PREC(TOK_EXPONENT)
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|| prec == PREC(TOK_CONDITIONAL));
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return prec == PREC(TOK_ASSIGN)
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|| prec == PREC(TOK_EXPONENT)
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|| prec == PREC(TOK_CONDITIONAL);
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}
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typedef struct {
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arith_t val;
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arith_t contidional_second_val;
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char contidional_second_val_initialized;
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char *var; /* if NULL then is regular number,
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else is variable name */
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} v_n_t;
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/* We acquire second_val only when "expr1 : expr2" part
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* of ternary ?: op is evaluated.
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* We treat ?: as two binary ops: (expr ? (expr1 : expr2)).
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* ':' produces a new value which has two parts, val and second_val;
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* then '?' selects one of them based on its left side.
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*/
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arith_t second_val;
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char second_val_present;
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/* If NULL then it's just a number, else it's a named variable */
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char *var;
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} var_or_num_t;
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typedef struct remembered_name {
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struct remembered_name *next;
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@ -248,7 +255,7 @@ static arith_t FAST_FUNC
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evaluate_string(arith_state_t *math_state, const char *expr);
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static const char*
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arith_lookup_val(arith_state_t *math_state, v_n_t *t)
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arith_lookup_val(arith_state_t *math_state, var_or_num_t *t)
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{
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if (t->var) {
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const char *p = lookupvar(t->var);
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@ -290,27 +297,28 @@ arith_lookup_val(arith_state_t *math_state, v_n_t *t)
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* stack. For an unary operator it will only change the top element, but a
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* binary operator will pop two arguments and push the result */
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static NOINLINE const char*
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arith_apply(arith_state_t *math_state, operator op, v_n_t *numstack, v_n_t **numstackptr)
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arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_or_num_t **numstackptr)
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{
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#define NUMPTR (*numstackptr)
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v_n_t *numptr_m1;
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arith_t numptr_val, rez;
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var_or_num_t *top_of_stack;
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arith_t rez;
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const char *err;
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/* There is no operator that can work without arguments */
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if (NUMPTR == numstack)
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goto err;
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numptr_m1 = NUMPTR - 1;
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/* Check operand is var with noninteger value */
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err = arith_lookup_val(math_state, numptr_m1);
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top_of_stack = NUMPTR - 1;
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/* Resolve name to value, if needed */
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err = arith_lookup_val(math_state, top_of_stack);
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if (err)
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return err;
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rez = numptr_m1->val;
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rez = top_of_stack->val;
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if (op == TOK_UMINUS)
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rez *= -1;
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rez = -rez;
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else if (op == TOK_NOT)
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rez = !rez;
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else if (op == TOK_BNOT)
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@ -321,112 +329,119 @@ arith_apply(arith_state_t *math_state, operator op, v_n_t *numstack, v_n_t **num
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rez--;
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else if (op != TOK_UPLUS) {
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/* Binary operators */
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arith_t right_side_val;
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char bad_second_val;
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/* check and binary operators need two arguments */
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if (numptr_m1 == numstack) goto err;
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/* Binary operators need two arguments */
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if (top_of_stack == numstack)
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goto err;
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/* ...and they pop one */
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--NUMPTR;
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numptr_val = rez;
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if (op == TOK_CONDITIONAL) {
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if (!numptr_m1->contidional_second_val_initialized) {
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/* protect $((expr1 ? expr2)) without ": expr" */
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goto err;
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NUMPTR = top_of_stack; /* this decrements NUMPTR */
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bad_second_val = top_of_stack->second_val_present;
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if (op == TOK_CONDITIONAL) { /* ? operation */
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/* Make next if (...) protect against
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* $((expr1 ? expr2)) - that is, missing ": expr" */
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bad_second_val = !bad_second_val;
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}
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rez = numptr_m1->contidional_second_val;
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} else if (numptr_m1->contidional_second_val_initialized) {
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/* protect $((expr1 : expr2)) without "expr ? " */
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goto err;
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if (bad_second_val) {
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/* Protect against $((expr <not_?_op> expr1 : expr2)) */
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return "malformed ?: operator";
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}
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numptr_m1 = NUMPTR - 1;
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top_of_stack--; /* now points to left side */
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if (op != TOK_ASSIGN) {
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/* check operand is var with noninteger value for not '=' */
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err = arith_lookup_val(math_state, numptr_m1);
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/* Resolve left side value (unless the op is '=') */
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err = arith_lookup_val(math_state, top_of_stack);
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if (err)
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return err;
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}
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if (op == TOK_CONDITIONAL) {
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numptr_m1->contidional_second_val = rez;
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right_side_val = rez;
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rez = top_of_stack->val;
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if (op == TOK_CONDITIONAL) /* ? operation */
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rez = (rez ? right_side_val : top_of_stack[1].second_val);
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else if (op == TOK_CONDITIONAL_SEP) { /* : operation */
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if (top_of_stack == numstack) {
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/* Protect against $((expr : expr)) */
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return "malformed ?: operator";
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}
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rez = numptr_m1->val;
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if (op == TOK_BOR || op == TOK_OR_ASSIGN)
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rez |= numptr_val;
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top_of_stack->second_val_present = op;
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top_of_stack->second_val = right_side_val;
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}
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else if (op == TOK_BOR || op == TOK_OR_ASSIGN)
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rez |= right_side_val;
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else if (op == TOK_OR)
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rez = numptr_val || rez;
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rez = right_side_val || rez;
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else if (op == TOK_BAND || op == TOK_AND_ASSIGN)
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rez &= numptr_val;
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rez &= right_side_val;
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else if (op == TOK_BXOR || op == TOK_XOR_ASSIGN)
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rez ^= numptr_val;
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rez ^= right_side_val;
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else if (op == TOK_AND)
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rez = rez && numptr_val;
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rez = rez && right_side_val;
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else if (op == TOK_EQ)
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rez = (rez == numptr_val);
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rez = (rez == right_side_val);
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else if (op == TOK_NE)
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rez = (rez != numptr_val);
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rez = (rez != right_side_val);
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else if (op == TOK_GE)
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rez = (rez >= numptr_val);
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rez = (rez >= right_side_val);
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else if (op == TOK_RSHIFT || op == TOK_RSHIFT_ASSIGN)
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rez >>= numptr_val;
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rez >>= right_side_val;
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else if (op == TOK_LSHIFT || op == TOK_LSHIFT_ASSIGN)
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rez <<= numptr_val;
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rez <<= right_side_val;
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else if (op == TOK_GT)
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rez = (rez > numptr_val);
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rez = (rez > right_side_val);
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else if (op == TOK_LT)
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rez = (rez < numptr_val);
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rez = (rez < right_side_val);
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else if (op == TOK_LE)
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rez = (rez <= numptr_val);
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rez = (rez <= right_side_val);
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else if (op == TOK_MUL || op == TOK_MUL_ASSIGN)
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rez *= numptr_val;
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rez *= right_side_val;
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else if (op == TOK_ADD || op == TOK_PLUS_ASSIGN)
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rez += numptr_val;
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rez += right_side_val;
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else if (op == TOK_SUB || op == TOK_MINUS_ASSIGN)
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rez -= numptr_val;
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rez -= right_side_val;
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else if (op == TOK_ASSIGN || op == TOK_COMMA)
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rez = numptr_val;
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else if (op == TOK_CONDITIONAL_SEP) {
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if (numptr_m1 == numstack) {
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/* protect $((expr : expr)) without "expr ? " */
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goto err;
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}
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numptr_m1->contidional_second_val_initialized = op;
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numptr_m1->contidional_second_val = numptr_val;
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} else if (op == TOK_CONDITIONAL) {
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rez = rez ?
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numptr_val : numptr_m1->contidional_second_val;
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} else if (op == TOK_EXPONENT) {
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rez = right_side_val;
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else if (op == TOK_EXPONENT) {
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arith_t c;
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if (numptr_val < 0)
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if (right_side_val < 0)
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return "exponent less than 0";
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c = 1;
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while (--numptr_val >= 0)
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while (--right_side_val >= 0)
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c *= rez;
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rez = c;
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} else if (numptr_val == 0)
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}
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else if (right_side_val == 0)
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return "divide by zero";
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else if (op == TOK_DIV || op == TOK_DIV_ASSIGN)
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rez /= numptr_val;
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rez /= right_side_val;
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else if (op == TOK_REM || op == TOK_REM_ASSIGN)
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rez %= numptr_val;
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rez %= right_side_val;
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}
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if (tok_have_assign(op)) {
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if (is_assign_op(op)) {
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char buf[sizeof(arith_t)*3 + 2];
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if (numptr_m1->var == NULL) {
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if (top_of_stack->var == NULL) {
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/* Hmm, 1=2 ? */
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//TODO: actually, bash allows ++7 but for some reason it evals to 7, not 8
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goto err;
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}
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/* save to shell variable */
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sprintf(buf, arith_t_fmt, rez);
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setvar(numptr_m1->var, buf);
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/* after saving, make previous value for v++ or v-- */
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/* Save to shell variable */
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sprintf(buf, ARITH_FMT, rez);
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setvar(top_of_stack->var, buf);
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/* After saving, make previous value for v++ or v-- */
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if (op == TOK_POST_INC)
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rez--;
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else if (op == TOK_POST_DEC)
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rez++;
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}
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numptr_m1->val = rez;
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/* erase var name, it is just a number now */
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numptr_m1->var = NULL;
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top_of_stack->val = rez;
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/* Erase var name, it is just a number now */
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top_of_stack->var = NULL;
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return NULL;
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err:
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return "arithmetic syntax error";
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@ -499,16 +514,17 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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const char *start_expr = expr = skip_whitespace(expr);
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unsigned expr_len = strlen(expr) + 2;
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/* Stack of integers */
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/* The proof that there can be no more than strlen(startbuf)/2+1 integers
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* in any given correct or incorrect expression is left as an exercise to
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* the reader. */
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v_n_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
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v_n_t *numstackptr = numstack;
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/* The proof that there can be no more than strlen(startbuf)/2+1
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* integers in any given correct or incorrect expression
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* is left as an exercise to the reader. */
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var_or_num_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
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var_or_num_t *numstackptr = numstack;
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/* Stack of operator tokens */
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operator *const stack = alloca(expr_len * sizeof(stack[0]));
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operator *stackptr = stack;
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*stackptr++ = lasttok = TOK_LPAREN; /* start off with a left paren */
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/* Start with a left paren */
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*stackptr++ = lasttok = TOK_LPAREN;
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errmsg = NULL;
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while (1) {
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@ -521,7 +537,7 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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arithval = *expr;
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if (arithval == '\0') {
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if (expr == start_expr) {
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/* Null expression. */
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/* Null expression */
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numstack->val = 0;
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goto ret;
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}
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@ -558,7 +574,7 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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safe_strncpy(numstackptr->var, expr, var_name_size);
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expr = p;
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num:
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numstackptr->contidional_second_val_initialized = 0;
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numstackptr->second_val_present = 0;
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numstackptr++;
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lasttok = TOK_NUM;
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continue;
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@ -577,21 +593,32 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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/* Should be an operator */
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p = op_tokens;
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while (1) {
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const char *e = expr;
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// TODO: bash allows 7+++v, treats it as 7 + ++v
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// we treat it as 7++ + v and reject
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/* Compare expr to current op_tokens[] element */
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while (*p && *e == *p)
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p++, e++;
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if (*p == '\0') { /* match: operator is found */
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const char *e = expr;
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while (1) {
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if (*p == '\0') {
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/* Match: operator is found */
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expr = e;
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break;
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goto tok_found;
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}
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/* Go to next element of op_tokens[] */
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if (*p != *e)
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break;
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p++;
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e++;
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}
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/* No match, go to next element of op_tokens[] */
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while (*p)
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p++;
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p += 2; /* skip NUL and TOK_foo bytes */
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if (*p == '\0') /* no next element, operator not found */
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if (*p == '\0') {
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/* No next element, operator not found */
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//math_state->syntax_error_at = expr;
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goto err;
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}
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}
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tok_found:
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op = p[1]; /* fetch TOK_foo value */
|
||||
/* NB: expr now points past the operator */
|
||||
|
||||
@ -662,21 +689,21 @@ evaluate_string(arith_state_t *math_state, const char *expr)
|
||||
}
|
||||
errmsg = arith_apply(math_state, prev_op, numstack, &numstackptr);
|
||||
if (errmsg)
|
||||
goto ret;
|
||||
goto err_with_custom_msg;
|
||||
}
|
||||
if (op == TOK_RPAREN) {
|
||||
if (op == TOK_RPAREN)
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
|
||||
/* Push this operator to the stack and remember it. */
|
||||
/* Push this operator to the stack and remember it */
|
||||
*stackptr++ = lasttok = op;
|
||||
next: ;
|
||||
} /* while (1) */
|
||||
|
||||
err:
|
||||
numstack->val = -1;
|
||||
errmsg = "arithmetic syntax error";
|
||||
err_with_custom_msg:
|
||||
numstack->val = -1;
|
||||
ret:
|
||||
math_state->errmsg = errmsg;
|
||||
return numstack->val;
|
||||
|
||||
20
shell/math.h
20
shell/math.h
@ -9,19 +9,13 @@
|
||||
|
||||
/* The math library has just one function:
|
||||
*
|
||||
* arith_t arith(arith_state_t *states, const char *expr);
|
||||
* arith_t arith(arith_state_t *state, const char *expr);
|
||||
*
|
||||
* The expr argument is the math string to parse. All normal expansions must
|
||||
* be done already. i.e. no dollar symbols should be present.
|
||||
*
|
||||
* The state argument is a pointer to a struct of hooks for your shell (see below),
|
||||
* and a semi-detailed error code. Currently, those values are (for
|
||||
* compatibility, you should assume all negative values are errors):
|
||||
* 0 - no errors (yay!)
|
||||
* -1 - unspecified problem
|
||||
* -2 - divide by zero
|
||||
* -3 - exponent less than 0
|
||||
* -5 - expression recursion loop detected
|
||||
* and an error message string (NULL if no error).
|
||||
*
|
||||
* The function returns the answer to the expression. So if you called it
|
||||
* with the expression:
|
||||
@ -64,12 +58,6 @@
|
||||
* the regex (in C locale): ^[a-zA-Z_][a-zA-Z_0-9]*
|
||||
*/
|
||||
|
||||
/* To make your life easier when dealing with optional 64bit math support,
|
||||
* rather than assume that the type is "signed long" and you can always
|
||||
* use "%ld" to scan/print the value, use the arith_t helper defines. See
|
||||
* below for the exact things that are available.
|
||||
*/
|
||||
|
||||
#ifndef SHELL_MATH_H
|
||||
#define SHELL_MATH_H 1
|
||||
|
||||
@ -77,11 +65,11 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
|
||||
|
||||
#if ENABLE_SH_MATH_SUPPORT_64
|
||||
typedef long long arith_t;
|
||||
#define arith_t_fmt "%lld"
|
||||
#define ARITH_FMT "%lld"
|
||||
#define strto_arith_t strtoull
|
||||
#else
|
||||
typedef long arith_t;
|
||||
#define arith_t_fmt "%ld"
|
||||
#define ARITH_FMT "%ld"
|
||||
#define strto_arith_t strtoul
|
||||
#endif
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user