From cc318d3e7ee1006e98994f7d2e382a0a69445893 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Wed, 1 May 2024 00:09:30 +0200
Subject: rebel-parse: add support for different path roots

Distinguish relative (unprefixed), absolute (`::` prefix) and
section-specific (`recipe::`, `task::`) paths.
---
 crates/rebel-lang/src/scope.rs             | 12 ++++++++++++
 crates/rebel-parse/src/ast/mod.rs          |  9 +++++++++
 crates/rebel-parse/src/grammar/recipe.rs   | 13 ++++++++++++-
 crates/rebel-parse/src/grammar/tokenize.rs |  1 +
 crates/rebel-parse/src/token.rs            |  1 +
 5 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/crates/rebel-lang/src/scope.rs b/crates/rebel-lang/src/scope.rs
index ccf2064..4b47435 100644
--- a/crates/rebel-lang/src/scope.rs
+++ b/crates/rebel-lang/src/scope.rs
@@ -43,6 +43,10 @@ impl Default for Context {
 
 impl Context {
 	pub fn local_ident<'a>(path: &'a ast::Path) -> Option<ast::Ident<'a>> {
+		if path.root != ast::PathRoot::Relative {
+			return None;
+		}
+
 		let [ident] = path.components[..] else {
 			return None;
 		};
@@ -50,6 +54,10 @@ impl Context {
 	}
 
 	pub fn lookup_var(&self, path: &ast::Path) -> Option<&Var> {
+		if path.root != ast::PathRoot::Relative {
+			return None;
+		}
+
 		if path.components == [ast::Ident { name: "_" }] {
 			return None;
 		}
@@ -58,6 +66,10 @@ impl Context {
 	}
 
 	pub fn lookup_type(&self, path: &ast::Path) -> Option<&Type> {
+		if path.root != ast::PathRoot::Relative {
+			return None;
+		}
+
 		if path.components == [ast::Ident { name: "_" }] {
 			return Some(&Type::Free);
 		}
diff --git a/crates/rebel-parse/src/ast/mod.rs b/crates/rebel-parse/src/ast/mod.rs
index 4fa8e63..eb6a7bd 100644
--- a/crates/rebel-parse/src/ast/mod.rs
+++ b/crates/rebel-parse/src/ast/mod.rs
@@ -131,8 +131,17 @@ pub struct FuncParam<'a> {
 	pub typ: Type<'a>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PathRoot {
+	Absolute,
+	Relative,
+	Recipe,
+	Task,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Path<'a> {
+	pub root: PathRoot,
 	pub components: Vec<Ident<'a>>,
 }
 
diff --git a/crates/rebel-parse/src/grammar/recipe.rs b/crates/rebel-parse/src/grammar/recipe.rs
index b1ac32f..50a0694 100644
--- a/crates/rebel-parse/src/grammar/recipe.rs
+++ b/crates/rebel-parse/src/grammar/recipe.rs
@@ -164,7 +164,18 @@ peg::parser! {
 			}
 
 		rule path() -> ast::Path<'a>
-			= components:ident() ++ p2(':', ':') { ast::Path { components } }
+			= components:(ident() ++ p2(':', ':')) {
+				ast::Path { root: ast::PathRoot::Relative, components }
+			}
+			/ components:(p2(':', ':') ident:ident() { ident })+ {
+				ast::Path { root: ast::PathRoot::Absolute, components }
+			}
+			/ [Token::Keyword(Keyword::Recipe)] components:(p2(':', ':') ident:ident() { ident })* {
+				ast::Path { root: ast::PathRoot::Recipe, components }
+			}
+			/ [Token::Keyword(Keyword::Task)] components:(p2(':', ':') ident:ident() { ident })* {
+				ast::Path { root: ast::PathRoot::Task, components }
+			}
 
 		rule field() -> ast::Ident<'a>
 			= ident()
diff --git a/crates/rebel-parse/src/grammar/tokenize.rs b/crates/rebel-parse/src/grammar/tokenize.rs
index 8696a89..70df2c3 100644
--- a/crates/rebel-parse/src/grammar/tokenize.rs
+++ b/crates/rebel-parse/src/grammar/tokenize.rs
@@ -8,6 +8,7 @@ static KEYWORDS: phf::Map<&'static str, Keyword> = phf::phf_map! {
 	"let" => Keyword::Let,
 	"map" => Keyword::Map,
 	"mut" => Keyword::Mut,
+	"recipe" => Keyword::Recipe,
 	"set" =>  Keyword::Set,
 	"struct" => Keyword::Struct,
 	"task" => Keyword::Task,
diff --git a/crates/rebel-parse/src/token.rs b/crates/rebel-parse/src/token.rs
index cbdd932..2f86dbd 100644
--- a/crates/rebel-parse/src/token.rs
+++ b/crates/rebel-parse/src/token.rs
@@ -14,6 +14,7 @@ pub enum Keyword {
 	Let,
 	Map,
 	Mut,
+	Recipe,
 	Set,
 	Struct,
 	Task,
-- 
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