Add more string manipulation functions (#998)

README.adoc

@@ -854,10 +854,14 @@ The executable is at: /bin/just
 
 ==== String Manipulation
 
-- `uppercase(s)` - Convert `s` to uppercase.
 - `lowercase(s)` - Convert `s` to lowercase.
-- `trim(s)` - Remove leading and trailing whitespace from `s`.
 - `replace(s, from, to)` - Replace all occurrences of `from` in `s` to `to`.
+- `trim(s)` - Remove leading and trailing whitespace from `s`.
+- `trim_end_match(s, pat)` - Remove suffix of `s` matching `pat`.
+- `trim_end_matches(s, pat)` - Repeatedly remove suffixes of `s` matching `pat`.
+- `trim_start_match(s, pat)` - Remove prefix of `s` matching `pat`.
+- `trim_start_matches(s, pat)` - Repeatedly remove prefixes of `s` matching `pat`.
+- `uppercase(s)` - Convert `s` to uppercase.
 
 ==== Dotenv Integration
 

src/function.rs

@@ -28,6 +28,10 @@ lazy_static! {
     ("parent_directory", Unary(parent_directory)),
     ("replace", Ternary(replace)),
     ("trim", Unary(trim)),
+    ("trim_end_match", Binary(trim_end_match)),
+    ("trim_end_matches", Binary(trim_end_matches)),
+    ("trim_start_match", Binary(trim_start_match)),
+    ("trim_start_matches", Binary(trim_start_matches)),
     ("uppercase", Unary(uppercase)),
     ("without_extension", Unary(without_extension)),
   ]
@@ -197,6 +201,22 @@ fn trim(_context: &FunctionContext, s: &str) -> Result<String, String> {
   Ok(s.trim().to_owned())
 }
 
+fn trim_end_match(_context: &FunctionContext, s: &str, pat: &str) -> Result<String, String> {
+  Ok(s.strip_suffix(pat).unwrap_or(s).to_owned())
+}
+
+fn trim_end_matches(_context: &FunctionContext, s: &str, pat: &str) -> Result<String, String> {
+  Ok(s.trim_end_matches(pat).to_owned())
+}
+
+fn trim_start_match(_context: &FunctionContext, s: &str, pat: &str) -> Result<String, String> {
+  Ok(s.strip_prefix(pat).unwrap_or(s).to_owned())
+}
+
+fn trim_start_matches(_context: &FunctionContext, s: &str, pat: &str) -> Result<String, String> {
+  Ok(s.trim_start_matches(pat).to_owned())
+}
+
 fn uppercase(_context: &FunctionContext, s: &str) -> Result<String, String> {
   Ok(s.to_uppercase())
 }

tests/functions.rs

@@ -302,3 +302,37 @@ test! {
   stdout: "foofoofoo\n",
   stderr: "echo foofoofoo\n",
 }
+
+fn assert_eval_eq(expression: &str, result: &str) {
+  Test::new()
+    .justfile(format!("x := {}", expression))
+    .args(&["--evaluate", "x"])
+    .stdout(result)
+    .run();
+}
+
+#[test]
+fn trim_end_matches() {
+  assert_eval_eq("trim_end_matches('foo', 'o')", "f");
+  assert_eval_eq("trim_end_matches('fabab', 'ab')", "f");
+  assert_eval_eq("trim_end_matches('fbaabab', 'ab')", "fba");
+}
+
+#[test]
+fn trim_end_match() {
+  assert_eval_eq("trim_end_match('foo', 'o')", "fo");
+  assert_eval_eq("trim_end_match('fabab', 'ab')", "fab");
+}
+
+#[test]
+fn trim_start_matches() {
+  assert_eval_eq("trim_start_matches('oof', 'o')", "f");
+  assert_eval_eq("trim_start_matches('ababf', 'ab')", "f");
+  assert_eval_eq("trim_start_matches('ababbaf', 'ab')", "baf");
+}
+
+#[test]
+fn trim_start_match() {
+  assert_eval_eq("trim_start_match('oof', 'o')", "of");
+  assert_eval_eq("trim_start_match('ababf', 'ab')", "abf");
+}