almost implement all functions

1 files changed, 49 insertions, 0 deletions

diff --git a/src/makefile/pattern.rs b/src/makefile/pattern.rs
new file mode 100644
index 0000000..733721e
--- /dev/null
+++ b/src/makefile/pattern.rs
@@ -0,0 +1,49 @@
+use regex::{Captures, Regex};
+
+fn compile_pattern(pattern: &str) -> Regex {
+    let mut result = String::new();
+    for c in pattern.chars() {
+        match c {
+            // This is a nightmare, because we're escaping for regex syntax before we put
+            // things into result.
+
+            // We don't end with a backslash, so this is an unescaped wildcard.
+            '%' if !result.ends_with(r"\\") => {
+                result.push_str(r"(\w*)");
+            }
+
+            // We end with two backslashes, so this is an escaped backslash and then an
+            // unescaped wildcard.
+            '%' if result.ends_with(r"\\\\") => {
+                result = result.strip_suffix(r"\\\\").unwrap().to_string();
+                result.push_str(r"\\(\w*)");
+            }
+
+            // We end with one backslash, so this is an escaped wildcard.
+            '%' if result.ends_with(r"\\") => {
+                result = result.strip_suffix(r"\\").unwrap().to_string();
+                result.push('%');
+            }
+            _ => result.push_str(&regex::escape(&c.to_string())),
+        }
+    }
+    Regex::new(&result).expect("built invalid regex!")
+}
+
+pub(crate) fn r#match<'a>(pattern: &str, text: &'a str) -> Option<Captures<'a>> {
+    compile_pattern(pattern).captures(text)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn pattern_backslashes() {
+        let test_case = compile_pattern(r"the\%weird\\%pattern\\");
+        assert_eq!(test_case.to_string(), r"the%weird\\(\w*)pattern\\\\");
+
+        let hell = compile_pattern(r"\\\\%");
+        assert_eq!(hell.to_string(), r"\\\\\\(\w*)");
+    }
+}