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