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Introduce support for substring function - str_sub() (#152)

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This function takes in 3 arguments: the string, the position and the
length (of the substring). As a quick example, a call to the function

`str_sub('c programming', 3, 11)`

will return the string 'programming' as the substring to the string
that is provisioned to the function call.
This commit is contained in:
Derick Alangi 2021-06-29 13:48:41 +01:00 committed by GitHub
parent 273a31e588
commit f1bbafaa28
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 36 additions and 1 deletions
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26
src/pk_core.c
View File

@ -648,11 +648,34 @@ DEF(coreExit,
// String functions.
// -----------------
// TODO: substring.
DEF(coreStrSub,
"str_sub(str:string, pos:num, len:num) -> string\n"
"Returns a substring from a given string supplied. In addition, "
"the position and length of the substring are provided when this "
"function is called. For example: `str_sub(str, pos, len)`.") {
int64_t len, pos;
String* str = NULL;
if (!validateArgString(vm, 1, &str)) return;
if (!validateInteger(vm, ARG(2), &pos, "Argument 2")) return;
if (!validateInteger(vm, ARG(3), &len, "Argument 3")) return;
if (str->length < pos || str->length < len)
RET_ERR(newString(vm, "Index out of range."));
// Edge case, empty string.
if (len == 0) RET(VAR_OBJ(newStringLength(vm, "", 0)));
String* sub_str = newStringLength(vm, str->data + pos, (uint32_t)len);
RET(VAR_OBJ(sub_str));
}
DEF(coreStrChr,
"str_chr(value:num) -> string\n"
"Returns the ASCII string value of the integer argument.") {
int64_t num;
if (!validateInteger(vm, ARG(1), &num, "Argument 1")) return;
@ -1123,6 +1146,7 @@ void initializeCore(PKVM* vm) {
INITIALIZE_BUILTIN_FN("exit", coreExit, -1);
// String functions.
INITIALIZE_BUILTIN_FN("str_sub", coreStrSub, 3);
INITIALIZE_BUILTIN_FN("str_chr", coreStrChr, 1);
INITIALIZE_BUILTIN_FN("str_ord", coreStrOrd, 1);

11
tests/lang/core.pk
View File

@ -30,6 +30,16 @@ def fn(p1, p2, p3) end
assert(fn.name == "fn")
assert(fn.arity == 3)
## String functions
assert(str_sub('c programming', 2, 11) == 'programming')
assert(str_sub('foobarbaz', 2, 3) == 'oba')
assert(str_sub('abcdef', 1, 2) == 'bc')
assert(str_sub('I am a boy', 0, 4) == 'I am')
assert(str_sub('programming', 2, 0) == '')
assert(str_sub('foobar', 5, 0) == '')
assert(str_sub('foobar', 0, 6) == 'foobar')
assert(str_sub('', 0, 0) == '')
## range
r = 1..5
assert(r.as_list == [1, 2, 3, 4])
@ -73,3 +83,4 @@ end
# If we got here, that means all test were passed.
print('All TESTS PASSED')