[3320] | 1 | /* math.h - interface to shell math "library" -- this allows shells to share
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| 2 | * the implementation of arithmetic $((...)) expansions.
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| 3 | *
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| 4 | * This aims to be a POSIX shell math library as documented here:
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| 5 | * http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04
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| 6 | *
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| 7 | * See math.c for internal documentation.
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| 8 | */
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| 9 |
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| 10 | /* The math library has just one function:
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| 11 | *
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| 12 | * arith_t arith(arith_state_t *state, const char *expr);
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| 13 | *
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| 14 | * The expr argument is the math string to parse. All normal expansions must
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| 15 | * be done already. i.e. no dollar symbols should be present.
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| 16 | *
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| 17 | * The state argument is a pointer to a struct of hooks for your shell (see below),
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| 18 | * and an error message string (NULL if no error).
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| 19 | *
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| 20 | * The function returns the answer to the expression. So if you called it
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| 21 | * with the expression:
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| 22 | * "1 + 2 + 3"
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| 23 | * you would obviously get back 6.
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| 24 | */
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| 25 |
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| 26 | /* To add support to a shell, you need to implement three functions:
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| 27 | *
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| 28 | * lookupvar() - look up and return the value of a variable
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| 29 | *
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| 30 | * If the shell does:
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| 31 | * foo=123
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| 32 | * Then the code:
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| 33 | * const char *val = lookupvar("foo");
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| 34 | * will result in val pointing to "123"
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| 35 | *
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| 36 | * setvar() - set a variable to some value
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| 37 | *
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| 38 | * If the arithmetic expansion does something like:
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| 39 | * $(( i = 1))
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| 40 | * then the math code will make a call like so:
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| 41 | * setvar("i", "1", 0);
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| 42 | * The storage for the first two parameters are not allocated, so your
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| 43 | * shell implementation will most likely need to strdup() them to save.
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| 44 | *
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| 45 | * endofname() - return the end of a variable name from input
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| 46 | *
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| 47 | * The arithmetic code does not know about variable naming conventions.
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| 48 | * So when it is given an experession, it knows something is not numeric,
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| 49 | * but it is up to the shell to dictate what is a valid identifiers.
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| 50 | * So when it encounters something like:
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| 51 | * $(( some_var + 123 ))
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| 52 | * It will make a call like so:
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| 53 | * end = endofname("some_var + 123");
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| 54 | * So the shell needs to scan the input string and return a pointer to the
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| 55 | * first non-identifier string. In this case, it should return the input
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| 56 | * pointer with an offset pointing to the first space. The typical
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| 57 | * implementation will return the offset of first char that does not match
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| 58 | * the regex (in C locale): ^[a-zA-Z_][a-zA-Z_0-9]*
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| 59 | */
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| 60 |
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| 61 | #ifndef SHELL_MATH_H
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| 62 | #define SHELL_MATH_H 1
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| 63 |
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| 64 | PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
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| 65 |
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| 66 | #if ENABLE_SH_MATH_SUPPORT_64
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| 67 | typedef long long arith_t;
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| 68 | #define ARITH_FMT "%lld"
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| 69 | #define strto_arith_t strtoull
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| 70 | #else
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| 71 | typedef long arith_t;
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| 72 | #define ARITH_FMT "%ld"
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| 73 | #define strto_arith_t strtoul
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| 74 | #endif
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| 75 |
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| 76 | /* ash's and hush's endofname is the same, so... */
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| 77 | # define is_name(c) ((c) == '_' || isalpha((unsigned char)(c)))
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| 78 | # define is_in_name(c) ((c) == '_' || isalnum((unsigned char)(c)))
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| 79 | const char* FAST_FUNC endofname(const char *name);
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| 80 |
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| 81 | typedef const char* FAST_FUNC (*arith_var_lookup_t)(const char *name);
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| 82 | typedef void FAST_FUNC (*arith_var_set_t)(const char *name, const char *val);
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| 83 | //typedef const char* FAST_FUNC (*arith_var_endofname_t)(const char *name);
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| 84 |
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| 85 | typedef struct arith_state_t {
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| 86 | const char *errmsg;
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| 87 | arith_var_lookup_t lookupvar;
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| 88 | arith_var_set_t setvar;
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| 89 | // arith_var_endofname_t endofname;
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| 90 | void *list_of_recursed_names;
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| 91 | } arith_state_t;
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| 92 |
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| 93 | arith_t FAST_FUNC arith(arith_state_t *state, const char *expr);
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| 94 |
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| 95 | POP_SAVED_FUNCTION_VISIBILITY
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| 96 |
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| 97 | #endif
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