internal: rename

crates/parser/src/input.rs

@@ -0,0 +1,88 @@
+//! See [`Input`].
+
+use crate::SyntaxKind;
+
+#[allow(non_camel_case_types)]
+type bits = u64;
+
+/// Input for the parser -- a sequence of tokens.
+///
+/// As of now, parser doesn't have access to the *text* of the tokens, and makes
+/// decisions based solely on their classification. Unlike `LexerToken`, the
+/// `Tokens` doesn't include whitespace and comments. Main input to the parser.
+///
+/// Struct of arrays internally, but this shouldn't really matter.
+#[derive(Default)]
+pub struct Input {
+    kind: Vec<SyntaxKind>,
+    joint: Vec<bits>,
+    contextual_kind: Vec<SyntaxKind>,
+}
+
+/// `pub` impl used by callers to create `Tokens`.
+impl Input {
+    #[inline]
+    pub fn push(&mut self, kind: SyntaxKind) {
+        self.push_impl(kind, SyntaxKind::EOF)
+    }
+    #[inline]
+    pub fn push_ident(&mut self, contextual_kind: SyntaxKind) {
+        self.push_impl(SyntaxKind::IDENT, contextual_kind)
+    }
+    /// Sets jointness for the last token we've pushed.
+    ///
+    /// This is a separate API rather than an argument to the `push` to make it
+    /// convenient both for textual and mbe tokens. With text, you know whether
+    /// the *previous* token was joint, with mbe, you know whether the *current*
+    /// one is joint. This API allows for styles of usage:
+    ///
+    /// ```
+    /// // In text:
+    /// tokens.was_joint(prev_joint);
+    /// tokens.push(curr);
+    ///
+    /// // In MBE:
+    /// token.push(curr);
+    /// tokens.push(curr_joint)
+    /// ```
+    #[inline]
+    pub fn was_joint(&mut self) {
+        let n = self.len() - 1;
+        let (idx, b_idx) = self.bit_index(n);
+        self.joint[idx] |= 1 << b_idx;
+    }
+    #[inline]
+    fn push_impl(&mut self, kind: SyntaxKind, contextual_kind: SyntaxKind) {
+        let idx = self.len();
+        if idx % (bits::BITS as usize) == 0 {
+            self.joint.push(0);
+        }
+        self.kind.push(kind);
+        self.contextual_kind.push(contextual_kind);
+    }
+}
+
+/// pub(crate) impl used by the parser to consume `Tokens`.
+impl Input {
+    pub(crate) fn kind(&self, idx: usize) -> SyntaxKind {
+        self.kind.get(idx).copied().unwrap_or(SyntaxKind::EOF)
+    }
+    pub(crate) fn contextual_kind(&self, idx: usize) -> SyntaxKind {
+        self.contextual_kind.get(idx).copied().unwrap_or(SyntaxKind::EOF)
+    }
+    pub(crate) fn is_joint(&self, n: usize) -> bool {
+        let (idx, b_idx) = self.bit_index(n);
+        self.joint[idx] & 1 << b_idx != 0
+    }
+}
+
+impl Input {
+    fn bit_index(&self, n: usize) -> (usize, usize) {
+        let idx = n / (bits::BITS as usize);
+        let b_idx = n % (bits::BITS as usize);
+        (idx, b_idx)
+    }
+    fn len(&self) -> usize {
+        self.kind.len()
+    }
+}