1 files changed, 152 insertions, 0 deletions
diff --git a/vendor/rowan/examples/math.rs b/vendor/rowan/examples/math.rs
new file mode 100644
index 000000000..930c591b0
--- /dev/null
+++ b/vendor/rowan/examples/math.rs
@@ -0,0 +1,152 @@
+//! Example that takes the input
+//! 1 + 2 * 3 + 4
+//! and builds the tree
+//! - Marker(Root)
+//!   - Marker(Operation)
+//!     - Marker(Operation)
+//!       - "1" Token(Number)
+//!       - "+" Token(Add)
+//!       - Marker(Operation)
+//!         - "2" Token(Number)
+//!         - "*" Token(Mul)
+//!         - "3" Token(Number)
+//!     - "+" Token(Add)
+//!     - "4" Token(Number)
+
+use rowan::{GreenNodeBuilder, NodeOrToken};
+use std::iter::Peekable;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[allow(non_camel_case_types)]
+#[repr(u16)]
+enum SyntaxKind {
+    WHITESPACE = 0,
+
+    ADD,
+    SUB,
+    MUL,
+    DIV,
+
+    NUMBER,
+    ERROR,
+    OPERATION,
+    ROOT,
+}
+use SyntaxKind::*;
+
+impl From<SyntaxKind> for rowan::SyntaxKind {
+    fn from(kind: SyntaxKind) -> Self {
+        Self(kind as u16)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+enum Lang {}
+impl rowan::Language for Lang {
+    type Kind = SyntaxKind;
+    fn kind_from_raw(raw: rowan::SyntaxKind) -> Self::Kind {
+        assert!(raw.0 <= ROOT as u16);
+        unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
+    }
+    fn kind_to_raw(kind: Self::Kind) -> rowan::SyntaxKind {
+        kind.into()
+    }
+}
+
+type SyntaxNode = rowan::SyntaxNode<Lang>;
+#[allow(unused)]
+type SyntaxToken = rowan::SyntaxToken<Lang>;
+#[allow(unused)]
+type SyntaxElement = rowan::NodeOrToken<SyntaxNode, SyntaxToken>;
+
+struct Parser<I: Iterator<Item = (SyntaxKind, String)>> {
+    builder: GreenNodeBuilder<'static>,
+    iter: Peekable<I>,
+}
+impl<I: Iterator<Item = (SyntaxKind, String)>> Parser<I> {
+    fn peek(&mut self) -> Option<SyntaxKind> {
+        while self.iter.peek().map(|&(t, _)| t == WHITESPACE).unwrap_or(false) {
+            self.bump();
+        }
+        self.iter.peek().map(|&(t, _)| t)
+    }
+    fn bump(&mut self) {
+        if let Some((token, string)) = self.iter.next() {
+            self.builder.token(token.into(), string.as_str());
+        }
+    }
+    fn parse_val(&mut self) {
+        match self.peek() {
+            Some(NUMBER) => self.bump(),
+            _ => {
+                self.builder.start_node(ERROR.into());
+                self.bump();
+                self.builder.finish_node();
+            }
+        }
+    }
+    fn handle_operation(&mut self, tokens: &[SyntaxKind], next: fn(&mut Self)) {
+        let checkpoint = self.builder.checkpoint();
+        next(self);
+        while self.peek().map(|t| tokens.contains(&t)).unwrap_or(false) {
+            self.builder.start_node_at(checkpoint, OPERATION.into());
+            self.bump();
+            next(self);
+            self.builder.finish_node();
+        }
+    }
+    fn parse_mul(&mut self) {
+        self.handle_operation(&[MUL, DIV], Self::parse_val)
+    }
+    fn parse_add(&mut self) {
+        self.handle_operation(&[ADD, SUB], Self::parse_mul)
+    }
+    fn parse(mut self) -> SyntaxNode {
+        self.builder.start_node(ROOT.into());
+        self.parse_add();
+        self.builder.finish_node();
+
+        SyntaxNode::new_root(self.builder.finish())
+    }
+}
+
+fn print(indent: usize, element: SyntaxElement) {
+    let kind: SyntaxKind = element.kind().into();
+    print!("{:indent$}", "", indent = indent);
+    match element {
+        NodeOrToken::Node(node) => {
+            println!("- {:?}", kind);
+            for child in node.children_with_tokens() {
+                print(indent + 2, child);
+            }
+        }
+
+        NodeOrToken::Token(token) => println!("- {:?} {:?}", token.text(), kind),
+    }
+}
+
+fn main() {
+    let ast = Parser {
+        builder: GreenNodeBuilder::new(),
+        iter: vec![
+            // 1 + 2 * 3 + 4
+            (NUMBER, "1".into()),
+            (WHITESPACE, " ".into()),
+            (ADD, "+".into()),
+            (WHITESPACE, " ".into()),
+            (NUMBER, "2".into()),
+            (WHITESPACE, " ".into()),
+            (MUL, "*".into()),
+            (WHITESPACE, " ".into()),
+            (NUMBER, "3".into()),
+            (WHITESPACE, " ".into()),
+            (ADD, "+".into()),
+            (WHITESPACE, " ".into()),
+            (NUMBER, "4".into()),
+        ]
+        .into_iter()
+        .peekable(),
+    }
+    .parse();
+    print(0, ast.into());
+}