diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/gleam/string.gleam | 52 |
1 files changed, 36 insertions, 16 deletions
diff --git a/src/gleam/string.gleam b/src/gleam/string.gleam index 93c686f..dd292b5 100644 --- a/src/gleam/string.gleam +++ b/src/gleam/string.gleam @@ -121,22 +121,42 @@ pub external fn uppercase(String) -> String = pub external fn compare(String, String) -> order.Order = "gleam_stdlib" "compare_strings" -// TODO -// Take a substring given a start and end Grapheme indexes. Negative indexes -// are taken starting from the *end* of the list. -// -// ## Examples -// > slice("gleam", from: 1, to: 3) -// "lea" -// -// > slice("gleam", from: 1, to: 10) -// "leam" -// -// > slice("snakes on a plane!", from: -6, to: -1) -// "plane" -// -// -// pub fn slice(out_of string: String, from start: Int, end: Int) -> String {} +external fn erl_slice(String, Int, Int) -> String = + "string" "slice" + +/// Take a substring given a start and end Grapheme indexes. Negative indexes +/// are taken starting from the *end* of the list. +/// +/// ## Examples +/// > slice(from: "gleam", at_index: 1, length: 2) +/// "le" +/// +/// > slice(from: "gleam", at_index: 1, length: 10) +/// "leam" +/// +/// > slice(from: "gleam", at_index: 10, length: 3) +/// "" +/// +/// > slice(from: "gleam", at_index: -2, length: 2) +/// "am" +/// +/// > slice(from: "gleam", at_index: -12, length: 2) +/// "" +/// +/// +pub fn slice(from string: String, at_index idx: Int, length len: Int) -> String { + case idx < 0 { + True -> { + let translated_idx = length(string) + idx + case translated_idx < 0 { + True -> "" + False -> erl_slice(string, translated_idx, len) + } + } + False -> erl_slice(string, idx, len) + } +} + // TODO // Drop *n* Graphemes from the left side of a // |