| /* math.h - interface to shell math "library" -- this allows shells to share |
| * the implementation of arithmetic $((...)) expansions. |
| * |
| * This aims to be a POSIX shell math library as documented here: |
| * http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04 |
| * |
| * See math.c for internal documentation. |
| */ |
| |
| /* The math library has just one function: |
| * |
| * 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 an error message string (NULL if no error). |
| * |
| * 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 |
| * |
| * 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 |
| * |
| * 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 |
| * |
| * 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]* |
| */ |
| |
| #ifndef SHELL_MATH_H |
| #define SHELL_MATH_H 1 |
| |
| PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN |
| |
| #if ENABLE_FEATURE_SH_MATH_64 |
| typedef long long arith_t; |
| #define ARITH_FMT "%lld" |
| #define strto_arith_t strtoull |
| #else |
| typedef long arith_t; |
| #define ARITH_FMT "%ld" |
| #define strto_arith_t strtoul |
| #endif |
| |
| 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_state_t { |
| const char *errmsg; |
| arith_var_lookup_t lookupvar; |
| arith_var_set_t setvar; |
| // arith_var_endofname_t endofname; |
| void *list_of_recursed_names; |
| } arith_state_t; |
| |
| arith_t FAST_FUNC arith(arith_state_t *state, const char *expr); |
| |
| POP_SAVED_FUNCTION_VISIBILITY |
| |
| #endif |