parser

src/objects/macros.rs

@@ -0,0 +1,75 @@
+#[cfg_attr(test, derive(PartialEq, Debug))]
+pub struct Macros<'a> {
+    pub name: &'a str,
+    pub args: Option<&'a str>,
+}
+
+fn valid_name(ch: u8) -> bool {
+    ch.is_ascii_alphanumeric() || ch == b'-' && ch == b'_'
+}
+
+impl<'a> Macros<'a> {
+    pub fn parse(src: &'a str) -> Option<(Macros<'a>, usize)> {
+        starts_with!(src, "{{{");
+
+        expect!(src, 3, |c: u8| c.is_ascii_alphabetic());
+
+        let name = until_while!(src, 3, |c| c == b'}' || c == b'(', valid_name);
+
+        if src.as_bytes()[name] == b'}' {
+            expect!(src, name + 1, b'}');
+            expect!(src, name + 2, b'}');
+            Some((
+                Macros {
+                    name: &src[3..name],
+                    args: None,
+                },
+                name + 3,
+            ))
+        } else {
+            let end = find!(src, name, "}}}");
+            expect!(src, end - 1, b')');
+            Some((
+                Macros {
+                    name: &src[3..name],
+                    args: if name == end {
+                        None
+                    } else {
+                        Some(&src[name + 1..end - 1])
+                    },
+                },
+                end + 3,
+            ))
+        }
+    }
+}
+
+#[test]
+fn parse() {
+    assert_eq!(
+        Macros::parse("{{{poem(red,blue)}}}").unwrap(),
+        (
+            Macros {
+                name: "poem",
+                args: Some("red,blue")
+            },
+            "{{{poem(red,blue)}}}".len()
+        )
+    );
+    assert_eq!(
+        Macros::parse("{{{author}}}").unwrap(),
+        (
+            Macros {
+                name: "author",
+                args: None,
+            },
+            "{{{author}}}".len()
+        )
+    );
+    assert!(Macros::parse("{{author}}}").is_none());
+    assert!(Macros::parse("{{{0uthor}}}").is_none());
+    assert!(Macros::parse("{{{author}}").is_none());
+    assert!(Macros::parse("{{{poem(}}}").is_none());
+    assert!(Macros::parse("{{{poem)}}}").is_none());
+    // FIXME: assert_eq!(Macros::parse("{{{poem())}}}"), None);
+}