[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
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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:
+ * 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_SH_MATH_SUPPORT_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
+
+/* ash's and hush's endofname is the same, so... */
+# define is_name(c) ((c) == '_' || isalpha((unsigned char)(c)))
+# define is_in_name(c) ((c) == '_' || isalnum((unsigned char)(c)))
+const char* FAST_FUNC endofname(const char *name);
+
+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