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/* 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:
* 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
typedef long long arith_t;
#define ARITH_FMT "%lld"
#define strto_arith_t strtoull
typedef long arith_t;
#define ARITH_FMT "%ld"
#define strto_arith_t strtoul
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);