1 files changed, 236 insertions, 0 deletions
diff --git a/src/makefile/token.rs b/src/makefile/token.rs
new file mode 100644
index 0000000..3f69b50
--- /dev/null
+++ b/src/makefile/token.rs
@@ -0,0 +1,236 @@
+use std::str::FromStr;
+
+use nom::{
+    Finish, IResult,
+    branch::alt,
+    bytes::complete::{tag, take_till1, take_while1},
+    character::complete::anychar,
+    combinator::{all_consuming, map, opt, verify},
+    multi::many1,
+    sequence::{delimited, pair, preceded, separated_pair},
+};
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct TokenString(Vec<Token>);
+
+impl TokenString {
+    pub fn tokens(&self) -> impl Iterator<Item=&Token> {
+        self.0.iter()
+    }
+
+    pub fn first_token_mut(&mut self) -> &mut Token {
+        &mut self.0[0]
+    }
+
+    pub fn split_once(&self, delimiter: char) -> Option<(TokenString, TokenString)> {
+        let mut result0 = vec![];
+        let mut iter = self.0.iter();
+        while let Some(t) = iter.next() {
+            match t {
+                Token::Text(text) if text.contains(delimiter) => {
+                    let split_text = text.splitn(2, delimiter);
+                    let pieces = split_text.collect::<Vec<_>>();
+                    assert_eq!(pieces.len(), 2, "wrong number of pieces!");
+                    result0.push(Token::Text(pieces[0].into()));
+                    let mut result1 = vec![Token::Text(pieces[1].into())];
+                    result1.extend(iter.cloned());
+                    return Some((TokenString(result0), TokenString(result1)));
+                }
+                _ => result0.push(t.clone()),
+            }
+        }
+        None
+    }
+}
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum Token {
+    Text(String),
+    MacroExpansion {
+        name: String,
+        replacement: Option<(TokenString, TokenString)>,
+    },
+}
+
+fn macro_name(input: &str) -> IResult<&str, &str> {
+    // POSIX says "periods, underscores, digits, and alphabetics from the portable character set"
+    take_while1(|c: char| {
+        c == '.' || c == '_' || c.is_alphanumeric()
+    })(input)
+}
+
+fn macro_expansion_body<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    let subst = preceded(tag(":"), separated_pair(tokens_but_not('='), tag("="), tokens_but_not(end)));
+    map(
+        pair(macro_name, opt(subst)),
+        |(name, replacement)| Token::MacroExpansion { name: name.into(), replacement },
+    )
+}
+
+fn parens_macro_expansion(input: &str) -> IResult<&str, Token> {
+    delimited(tag("$("), macro_expansion_body(')'), tag(")"))(input)
+}
+
+fn braces_macro_expansion(input: &str) -> IResult<&str, Token> {
+    delimited(tag("${"), macro_expansion_body('}'), tag("}"))(input)
+}
+
+fn tiny_macro_expansion(input: &str) -> IResult<&str, Token> {
+    let raw = preceded(tag("$"), verify(anychar, |&c| c != '(' && c != '{'));
+    map(raw, |c| {
+        if c == '$' {
+            Token::Text("$".into())
+        } else {
+            Token::MacroExpansion {
+                name: c.to_string(),
+                replacement: None,
+            }
+        }
+    })(input)
+}
+
+fn macro_expansion(input: &str) -> IResult<&str, Token> {
+    alt((tiny_macro_expansion, parens_macro_expansion, braces_macro_expansion))(input)
+}
+
+fn text(input: &str) -> IResult<&str, Token> {
+    map(take_till1(|c| c == '$'), |x: &str| Token::Text(x.into()))(input)
+}
+
+fn text_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    map(take_till1(move |c| c == '$' || c == end), |x: &str| Token::Text(x.into()))
+}
+
+fn single_token(input: &str) -> IResult<&str, Token> {
+    alt((text, macro_expansion))(input)
+}
+
+fn single_token_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    alt((text_but_not(end), macro_expansion))
+}
+
+fn empty_tokens(input: &str) -> IResult<&str, TokenString> {
+    map(tag(""), |_| TokenString(vec![Token::Text(String::new())]))(input)
+}
+
+fn tokens(input: &str) -> IResult<&str, TokenString> {
+    alt((map(many1(single_token), TokenString), empty_tokens))(input)
+}
+
+fn tokens_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, TokenString> {
+    alt((map(many1(single_token_but_not(end)), TokenString), empty_tokens))
+}
+
+fn full_text_tokens(input: &str) -> IResult<&str, TokenString> {
+    all_consuming(tokens)(input)
+}
+
+pub fn tokenize(input: &str) -> TokenString {
+    // TODO handle errors gracefully
+    let (_, result) = full_text_tokens(input).expect("couldn't parse");
+    result
+}
+
+impl FromStr for TokenString {
+    // TODO figure out how to get nom errors working (Error<&str> doesn't work because lifetimes)
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        full_text_tokens(s).finish()
+            .map(|(_, x)| x)
+            .map_err(|_| ())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::{Token, TokenString, tokenize};
+
+    impl From<Vec<Token>> for TokenString {
+        fn from(x: Vec<Token>) -> Self {
+            TokenString(x)
+        }
+    }
+
+    fn token_text(text: impl Into<String>) -> Token {
+        Token::Text(text.into())
+    }
+
+    fn token_macro_expansion(name: impl Into<String>) -> Token {
+        Token::MacroExpansion { name: name.into(), replacement: None }
+    }
+
+    fn token_macro_expansion_replacement(name: impl Into<String>,
+                                         subst1: impl Into<TokenString>,
+                                         subst2: impl Into<TokenString>) -> Token {
+        Token::MacroExpansion { name: name.into(), replacement: Some((subst1.into(), subst2.into())) }
+    }
+
+    #[test]
+    fn no_macros() {
+        let text = "This is an example sentence! There aren't macros in it at all!";
+        let tokens = tokenize(text);
+        assert_eq!(tokens, TokenString(vec![token_text(text)]));
+    }
+
+    #[test]
+    fn no_replacement() {
+        let text = "This is a $Q sentence! There are $(BORING) macros in it at ${YEET}!";
+        let tokens = tokenize(text);
+        assert_eq!(tokens, TokenString(vec![
+            token_text("This is a "),
+            token_macro_expansion("Q"),
+            token_text(" sentence! There are "),
+            token_macro_expansion("BORING"),
+            token_text(" macros in it at "),
+            token_macro_expansion("YEET"),
+            token_text("!"),
+        ]));
+    }
+
+    #[test]
+    fn escaped() {
+        let text = "This costs $$2 to run, which isn't ideal";
+        let tokens = tokenize(text);
+        assert_eq!(tokens, TokenString(vec![
+            token_text("This costs "),
+            token_text("$"),
+            token_text("2 to run, which isn't ideal"),
+        ]));
+    }
+
+    #[test]
+    fn replacement() {
+        let text = "Can I get a $(DATA:.c=.oof) in this ${SWAG:.yolo=}";
+        let tokens = tokenize(text);
+        assert_eq!(tokens, TokenString(vec![
+            token_text("Can I get a "),
+            token_macro_expansion_replacement("DATA", vec![token_text(".c")], vec![token_text(".oof")]),
+            token_text(" in this "),
+            token_macro_expansion_replacement("SWAG", vec![token_text(".yolo")], vec![token_text("")]),
+        ]));
+    }
+
+    #[test]
+    fn hell() {
+        let text = "$(OOF:${ouch:hi=hey} there=$(owie:$(my)=${bones})), bro.";
+        let tokens = tokenize(text);
+        assert_eq!(tokens, TokenString(vec![
+            token_macro_expansion_replacement(
+                "OOF",
+                vec![
+                    token_macro_expansion_replacement("ouch", vec![token_text("hi")], vec![token_text("hey")]),
+                    token_text(" there"),
+                ],
+                vec![
+                    token_macro_expansion_replacement(
+                        "owie",
+                        vec![token_macro_expansion("my")],
+                        vec![token_macro_expansion("bones")],
+                    ),
+                ],
+            ),
+            token_text(", bro."),
+        ]));
+    }
+}