diff options
Diffstat (limited to 'shell/math.h')
| -rw-r--r-- | shell/math.h | 91 |
1 files changed, 45 insertions, 46 deletions
diff --git a/shell/math.h b/shell/math.h index 96088b4..9f3da7f 100644 --- a/shell/math.h +++ b/shell/math.h @@ -9,61 +9,59 @@ /* The math library has just one function: * - * arith_t arith(const char *expr, int *perrcode, arith_eval_hooks_t *hooks); + * arith_t arith(arith_state_t *states, const char *expr); * - * The first argument is the math string to parse. All normal expansions must - * be done already. i.e. no dollar symbols should be present. + * 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 second argument is a semi-detailed error description in case something - * goes wrong in the parsing steps. 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 + * 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 * - * The third argument is a struct pointer of hooks for your shell (see below). - * - * The function returns the answer to the expression. So if you called it - * with the expression: - * "1 + 2 + 3" - * You would obviously get back 6. + * The function returns the answer to the expression. So if you called it + * with the expression: + * "1 + 2 + 3" + * you would obviously get back 6. */ /* To add support to a shell, you need to implement three functions: * - * lookupvar() - look up and return the value of a variable + * lookupvar() - look up and return the value of a variable * - * If the shell does: - * foo=123 - * Then the code: - * const char *val = lookupvar("foo"); - * Will result in val pointing to "123" + * If the shell does: + * foo=123 + * Then the code: + * const char *val = lookupvar("foo"); + * will result in val pointing to "123" * - * setvar() - set a variable to some value + * setvar() - set a variable to some value * - * If the arithmetic expansion does something like: - * $(( i = 1)) - * Then the math code will make a call like so: - * setvar("i", "1", 0); - * The storage for the first two parameters are not allocated, so your - * shell implementation will most likely need to strdup() them to save. + * If the arithmetic expansion does something like: + * $(( i = 1)) + * then the math code will make a call like so: + * setvar("i", "1", 0); + * The storage for the first two parameters are not allocated, so your + * shell implementation will most likely need to strdup() them to save. * - * endofname() - return the end of a variable name from input + * endofname() - return the end of a variable name from input * - * The arithmetic code does not know about variable naming conventions. - * So when it is given an experession, it knows something is not numeric, - * but it is up to the shell to dictate what is a valid identifiers. - * So when it encounters something like: - * $(( some_var + 123 )) - * It will make a call like so: - * end = endofname("some_var + 123"); - * So the shell needs to scan the input string and return a pointer to the - * first non-identifier string. In this case, it should return the input - * pointer with an offset pointing to the first space. The typical - * implementation will return the offset of first char that does not match - * the regex (in C locale): ^[a-zA-Z_][a-zA-Z_0-9]* + * The arithmetic code does not know about variable naming conventions. + * So when it is given an experession, it knows something is not numeric, + * but it is up to the shell to dictate what is a valid identifiers. + * So when it encounters something like: + * $(( some_var + 123 )) + * It will make a call like so: + * end = endofname("some_var + 123"); + * So the shell needs to scan the input string and return a pointer to the + * first non-identifier string. In this case, it should return the input + * pointer with an offset pointing to the first space. The typical + * implementation will return the offset of first char that does not match + * 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, @@ -96,13 +94,14 @@ typedef const char* FAST_FUNC (*arith_var_lookup_t)(const char *name); typedef void FAST_FUNC (*arith_var_set_t)(const char *name, const char *val); //typedef const char* FAST_FUNC (*arith_var_endofname_t)(const char *name); -typedef struct arith_eval_hooks { +typedef struct arith_state_t { arith_var_lookup_t lookupvar; arith_var_set_t setvar; // arith_var_endofname_t endofname; -} arith_eval_hooks_t; + int errcode; +} arith_state_t; -arith_t arith(const char *expr, int *perrcode, arith_eval_hooks_t*); +arith_t arith(arith_state_t *state, const char *expr); POP_SAVED_FUNCTION_VISIBILITY |