Lexer scaffold

src/lexer.rs

@@ -0,0 +1,10 @@
+use {Token, TextUnit};
+use syntax_kinds::*;
+
+pub fn next_token(text: &str) -> Token {
+    let c = text.chars().next().unwrap();
+    Token {
+        kind: IDENT,
+        len: TextUnit::len_of_char(c),
+    }
+}

src/lib.rs

@@ -1,7 +1,8 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
-    }
-}
+mod text;
+mod tree;
+mod lexer;
+
+pub mod syntax_kinds;
+pub use text::TextUnit;
+pub use tree::{SyntaxKind, Token};
+pub use lexer::next_token;

src/syntax_kinds.rs

@@ -0,0 +1,16 @@
+use tree::{SyntaxKind, SyntaxInfo};
+
+pub const IDENT: SyntaxKind = SyntaxKind(1);
+pub const WHITESPACE: SyntaxKind = SyntaxKind(2);
+
+
+static IDENT_INFO: SyntaxInfo = SyntaxInfo {
+    name: "IDENT",
+};
+
+pub(crate) fn syntax_info(kind: SyntaxKind) -> &'static SyntaxInfo {
+    match kind {
+        IDENT => &IDENT_INFO,
+        _ => unreachable!(),
+    }
+}

src/text.rs

@@ -0,0 +1,32 @@
+use std::fmt;
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct TextUnit(u32);
+
+impl TextUnit {
+    pub fn len_of_char(c: char) -> TextUnit {
+        TextUnit(c.len_utf8() as u32)
+    }
+
+    pub fn new(val: u32) -> TextUnit {
+        TextUnit(val)
+    }
+}
+
+impl fmt::Debug for TextUnit {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        <Self as fmt::Display>::fmt(self, f)
+    }
+}
+
+impl fmt::Display for TextUnit {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl From<TextUnit> for u32 {
+    fn from(tu: TextUnit) -> u32 {
+        tu.0
+    }
+}

src/tree.rs

@@ -0,0 +1,31 @@
+use text::{TextUnit};
+use syntax_kinds::syntax_info;
+
+use std::fmt;
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct SyntaxKind(pub(crate) u32);
+
+impl SyntaxKind {
+    fn info(self) -> &'static SyntaxInfo {
+        syntax_info(self)
+    }
+}
+
+impl fmt::Debug for SyntaxKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let name = self.info().name;
+        f.write_str(name)
+    }
+}
+
+
+pub(crate) struct SyntaxInfo {
+    pub name: &'static str,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Token {
+    pub kind: SyntaxKind,
+    pub len: TextUnit,
+}

tests/lexer.rs

@@ -1,9 +1,13 @@
 extern crate file;
 #[macro_use(assert_diff)]
 extern crate difference;
+extern crate libsyntax2;
 
 use std::path::{PathBuf, Path};
 use std::fs::read_dir;
+use std::fmt::Write;
+
+use libsyntax2::{Token, next_token};
 
 #[test]
 fn lexer_tests() {
@@ -46,10 +50,22 @@ fn lexer_test_case(path: &Path) {
     )
 }
 
-fn tokenize(text: &str) -> Vec<()> {
-    Vec::new()
+fn tokenize(text: &str) -> Vec<Token> {
+    let mut text = text;
+    let mut acc = Vec::new();
+    while !text.is_empty() {
+        let token = next_token(text);
+        acc.push(token);
+        let len: u32 = token.len.into();
+        text = &text[len as usize..];
+    }
+    acc
 }
 
-fn dump_tokens(tokens: &[()]) -> String {
-    "IDENT 5\nKEYWORD 1\nIDENT 5\n".to_string()
+fn dump_tokens(tokens: &[Token]) -> String {
+    let mut acc = String::new();
+    for token in tokens {
+        write!(acc, "{:?} {}\n", token.kind, token.len).unwrap()
+    }
+    acc
 }