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// SPDX-License-Identifier: MPL-2.0
// (c) Hare authors <https://harelang.org>
// Returns the offset of the first instance of "needle" in a "haystack" of
// bytes, or void if it is not found.
export fn index(haystack: []u8, needle: (u8 | []u8)) (size | void) = {
return match (needle) {
case let b: u8 =>
yield index_byte(haystack, b);
case let b: []u8 =>
yield index_slice(haystack, b);
};
};
fn index_byte(haystack: []u8, needle: u8) (size | void) = {
for (let i = 0z; i < len(haystack); i += 1) {
if (haystack[i] == needle) {
return i;
};
};
};
fn index_2bytes(haystack: []u8, needle: u16) (size | void) = {
if (len(haystack) > 1) {
let x = haystack[0]: u16;
for (let i = 1z; i < len(haystack); i += 1) {
x = x << 8 | haystack[i];
if (x == needle) {
return i - 1;
};
};
};
};
fn index_3bytes(haystack: []u8, needle: u32) (size | void) = {
if (len(haystack) > 2) {
let x = haystack[0]: u32 << 8 | haystack[1];
for (let i = 2z; i < len(haystack); i += 1) {
x = x << 16 >> 8 | haystack[i];
if (x == needle) {
return i - 2;
};
};
};
};
fn index_4bytes(haystack: []u8, needle: u32) (size | void) = {
if (len(haystack) > 3) {
let x = haystack[0]: u32 << 16 |
haystack[1]: u32 << 8 |
haystack[2];
for (let i = 3z; i < len(haystack); i += 1) {
x = x << 8 | haystack[i];
if (x == needle) {
return i - 3;
};
};
};
};
fn index_slice(haystack: []u8, b: []u8) (size | void) = {
switch (len(b)) {
case 0 =>
return 0;
case 1 =>
return index_byte(haystack, b[0]);
case 2 =>
return index_2bytes(haystack, b[0]: u16 << 8 | b[1]);
case 3 =>
return index_3bytes(
haystack,
b[0]: u32 << 16 | b[1]: u32 << 8 | b[2],
);
case 4 =>
return index_4bytes(
haystack,
b[0]: u32 << 24 | b[1]: u32 << 16 | b[2]: u32 << 8 | b[3],
);
case =>
return index_tw(haystack, b);
};
};
// Returns the offset of the last instance of "needle" in a "haystack" of
// bytes, or void if it is not found.
export fn rindex(haystack: []u8, needle: (u8 | []u8)) (size | void) = {
match (needle) {
case let b: u8 =>
return rindex_byte(haystack, b);
case let b: []u8 =>
return rindex_slice(haystack, b);
};
};
fn rindex_byte(haystack: []u8, needle: u8) (size | void) = {
for (let i = len(haystack); i > 0; i -= 1) {
if (haystack[i - 1] == needle) {
return i - 1;
};
};
};
fn rindex_slice(haystack: []u8, needle: []u8) (size | void) = {
for (let i = 0z; i + len(needle) <= len(haystack); i += 1) {
let r = len(haystack) - i;
if (equal(haystack[r - len(needle)..r], needle)) {
return r - len(needle);
};
};
};
@test fn index() void = {
// Bytes
const a: [4]u8 = [1, 3, 3, 7];
assert(index(a, 7) as size == 3);
assert(index(a, 42) is void);
assert(index([], 42) is void);
assert(rindex(a, 3) as size == 2);
assert(rindex(a, 42) is void);
assert(rindex([], 42) is void);
// Slices
const a: [4]u8 = [1, 1, 1, 2];
assert(rindex(a, [1, 1]) as size == 1);
assert(rindex(a, [1, 2]) as size == 2);
// len(haystack) < len(needle)
assert(index([], [1, 2, 3]) is void);
assert(index([1, 2, 3], [1, 2, 3, 4]) is void);
// len(haystack) == len(needle)
assert(index([42, 20], [42, 20]) as size == 0);
assert(index([1, 1, 1, 2], [1, 1, 1, 3]) is void);
assert(index([1, 42, 24], [42, 24]) as size == 1);
assert(index([1, 3, 3, 7], [3, 3]) as size == 1);
assert(index([1, 1, 1, 2], [1, 1, 2]) as size == 1);
assert(index([1, 1, 1, 3, 2], [1, 1, 1, 2]) is void);
const tests: [_](str, str) = [
("3214567844", "0123456789"),
("3214567889012345", "0123456789012345"),
("32145678890123456789", "01234567890123456789"),
("32145678890123456789012345678901234567890211", "01234567890123456789012345678901"),
("321456788901234567890123456789012345678911", "0123456789012345678901234567890"),
("abc", "x"),
("oxoxoxoxoxoxoxoxoxoxoxox", "oy"),
("x", "a"),
("x01234567x89", "0123456789"),
("xabcqxq", "abcqq"),
("xabxc", "abc"),
("xabxcqq", "abcqq"),
("xbc", "abc"),
("xbcd", "abcd"),
("xx012345678901234567890123456789012345678901234567890123456789012", "0123456789012345678901234567890123456xxx"),
("xyz012345678", "0123456789"),
("xyz0123456789012345678", "01234567890123456789"),
("xyz0123456789012345678901234567890", "01234567890123456789012345678901"),
];
for (let i = 0z; i < len(tests); i += 1) {
let haystack = *(&tests[i].0: *[]u8);
let needle = *(&tests[i].1: *[]u8);
index(haystack, needle) as void;
};
const tests: [_](str, str, size) = [
("", "", 0),
("01234567", "01234567", 0),
("0123456789", "0123456789", 0),
("0123456789012345", "0123456789012345", 0),
("01234567890123456789", "01234567890123456789", 0),
("0123456789012345678901234567890", "0123456789012345678901234567890", 0),
("01234567890123456789012345678901", "01234567890123456789012345678901", 0),
("ab", "ab", 0),
("abc", "a", 0),
("abc", "abc", 0),
("abc", "b", 1),
("abc", "c", 2),
("abcABCabc", "A", 3),
("abcd", "abcd", 0),
("abcqq", "abcqq", 0),
("barfoobarfoo", "foo", 3),
("foo", "", 0),
("foo", "foo", 0),
("foo", "o", 1),
("oofofoofooo", "f", 2),
("oofofoofooo", "foo", 4),
("oxoxoxoxoxoxoxoxoxoxoxoy", "oy", 22),
("x", "x", 0),
("x01234567", "01234567", 1),
("x0123456789", "0123456789", 1),
("x0123456789012345", "0123456789012345", 1),
("x01234567890123456789", "01234567890123456789", 1),
("x0123456789012345678901234567890", "0123456789012345678901234567890", 1),
("x01234567890123456789012345678901", "01234567890123456789012345678901", 1),
("x0123456789012345678901234567890x01234567890123456789012345678901", "01234567890123456789012345678901", 33),
("x012345678901234567890123456789x0123456789012345678901234567890", "0123456789012345678901234567890", 32),
("x0123456789012345678x01234567890123456789", "01234567890123456789", 21),
("x012345678901234x0123456789012345", "0123456789012345", 17),
("x012345678x0123456789", "0123456789", 11),
("x0123456x01234567", "01234567", 9),
("xab", "ab", 1),
("xabc", "abc", 1),
("xabcd", "abcd", 1),
("xabcqq", "abcqq", 1),
("xx012345678901234567890123456789012345678901234567890123456789012", "0123456789012345678901234567890123456789", 2),
("xx0123456789012345678901234567890123456789012345678901234567890120123456789012345678901234567890123456xxx", "0123456789012345678901234567890123456xxx", 65),
("xxxxxx012345678901234567890123456789012345678901234567890123456789012", "012345678901234567890123456789012345678901234567890123456789012", 6),
];
for (let i = 0z; i < len(tests); i += 1) {
let haystack = *(&tests[i].0: *[]u8);
let needle = *(&tests[i].1: *[]u8);
assert(index(haystack, needle) as size == tests[i].2);
};
};
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