18: Comments r=matklad a=matklad
This commit is contained in:
bors[bot] 2018-01-28 09:07:26 +00:00
commit bec9f09134
3 changed files with 59 additions and 4 deletions

View file

@ -51,8 +51,12 @@ impl Grammar {
write!(acc, " {},\n", scream(kind)).unwrap();
}
acc.push_str("\n");
acc.push_str(" TOMBSTONE = !0 - 1,\n");
acc.push_str(" EOF = !0,\n");
acc.push_str(" // Technical SyntaxKinds: they appear temporally during parsing,\n");
acc.push_str(" // but never end up in the final tree\n");
acc.push_str(" #[doc(hidden)]\n");
acc.push_str(" TOMBSTONE,\n");
acc.push_str(" #[doc(hidden)]\n");
acc.push_str(" EOF,\n");
acc.push_str("}\n");
acc.push_str("pub(crate) use self::SyntaxKind::*;\n");
acc.push_str("\n");

View file

@ -4,17 +4,64 @@ use {SyntaxKind, Token};
mod parser;
mod grammar;
/// `Parser` produces a flat list of `Event`s.
/// They are converted to a tree-structure in
/// a separate pass, via `TreeBuilder`.
#[derive(Debug)]
pub(crate) enum Event {
/// This event signifies the start of the node.
/// It should be either abandoned (in which case the
/// `kind` is `TOMBSTONE`, and the event is ignored),
/// or completed via a `Finish` event.
///
/// All tokens between a `Start` and a `Finish` would
/// become the children of the respective node.
///
/// For left-recursive syntactic constructs, the parser produces
/// a child node before it sees a parent. `forward_parent`
/// exists to allow to tweak parent-child relationships.
///
/// Consider this path
///
/// foo::bar
///
/// The events for it would look like this:
///
///
/// START(PATH) IDENT('foo') FINISH START(PATH) COLONCOLON IDENT('bar') FINISH
/// | /\
/// | |
/// +------forward-parent------+
///
/// And the tree would look like this
///
/// +--PATH---------+
/// | | |
/// | | |
/// | '::' 'bar'
/// |
/// PATH
/// |
/// 'foo'
///
/// See also `CompleteMarker::precede`.
Start {
kind: SyntaxKind,
forward_parent: Option<u32>,
},
/// Complete the previous `Start` event
Finish,
/// Produce a single leaf-element.
/// `n_raw_tokens` is used to glue complex contextual tokens.
/// For example, lexer tokenizes `>>` as `>`, `>`, and
/// `n_raw_tokens = 2` is used to produced a single `>>`.
Token {
kind: SyntaxKind,
n_raw_tokens: u8,
},
Error {
message: String,
},

View file

@ -92,8 +92,12 @@ pub enum SyntaxKind {
ALIAS,
VISIBILITY,
TOMBSTONE = !0 - 1,
EOF = !0,
// Technical SyntaxKinds: they appear temporally during parsing,
// but never end up in the final tree
#[doc(hidden)]
TOMBSTONE,
#[doc(hidden)]
EOF,
}
pub(crate) use self::SyntaxKind::*;