Merge pull request #22668 from github/tausbn/yeast-remove-support-for-fresh-literals

yeast: Remove support for fresh literals

Author: tausbn

shared/yeast-macros/src/lib.rs

@@ -40,7 +40,6 @@ pub fn query(input: TokenStream) -> TokenStream {
 /// ```text
 /// (kind "literal")             - leaf with static content
 /// (kind #{expr})               - leaf with computed content (expr.to_string())
-/// (kind $fresh)                - leaf with auto-generated unique name
 /// {expr}                       - embed a Rust expression, dispatched via
 ///                                the `IntoFieldIds` trait: `Id` pushes a
 ///                                single id; iterables (`Vec<Id>`,

shared/yeast-macros/src/parse.rs

@@ -422,7 +422,7 @@ fn parse_direct_node(
 }
 
 /// Parse the inside of a parenthesized node: `kind fields... children...`
-/// or `kind "literal"` or `kind $fresh`.
+/// or `kind "literal"`.
 fn parse_direct_node_inner(
     tokens: &mut Tokens,
     ctx: &Ident,
@@ -474,14 +474,6 @@ fn parse_direct_node_inner(
         });
     }
 
-    // Check for (kind $fresh)
-    if peek_is_dollar(tokens) {
-        tokens.next();
-        let name = expect_ident(tokens, "expected fresh variable name after $")?;
-        let name_str = name.to_string();
-        return Ok(quote! { #ctx.fresh(#kind_str, #name_str) });
-    }
-
     // Parse named fields
     let mut stmts = Vec::new();
     let mut field_args = Vec::new();
@@ -973,7 +965,7 @@ pub fn parse_rule_top(input: TokenStream) -> Result<TokenStream> {
                     let #ctx_ident = __user_ctx;
                     Ok(#guard)
                 }),
-                Box::new(|__ast: &mut yeast::Ast, mut __captures: yeast::captures::Captures, __fresh: &yeast::tree_builder::FreshScope, __source_range: Option<yeast::Range>, __user_ctx: &mut _, __translator: yeast::TranslatorHandle<'_, _>| {
+                Box::new(|__ast: &mut yeast::Ast, mut __captures: yeast::captures::Captures, __source_range: Option<yeast::Range>, __user_ctx: &mut _, __translator: yeast::TranslatorHandle<'_, _>| {
                     // Auto-translation prefix: recursively translate every
                     // captured node before invoking the user's transform body,
                     // except for `@@name` captures listed in `__skip` which the
@@ -985,7 +977,7 @@ pub fn parse_rule_top(input: TokenStream) -> Result<TokenStream> {
                     __translator.auto_translate_captures(&mut __captures, __ast, __user_ctx, __skip)?;
                     #(#raw_bindings)*
                     #(#translated_bindings)*
-                    let mut #ctx_ident = yeast::build::BuildCtx::with_translator(__ast, &__captures, __fresh, __source_range, __user_ctx, __translator);
+                    let mut #ctx_ident = yeast::build::BuildCtx::with_translator(__ast, &__captures, __source_range, __user_ctx, __translator);
                     let __result: Vec<yeast::Id> = { #transform_body };
                     let __result = #ctx_ident.finish_rule(__result);
                     Ok(__result)
@@ -1048,10 +1040,6 @@ fn peek_is_literal(tokens: &mut Tokens) -> bool {
     matches!(tokens.peek(), Some(TokenTree::Literal(_)))
 }
 
-fn peek_is_dollar(tokens: &mut Tokens) -> bool {
-    matches!(tokens.peek(), Some(TokenTree::Punct(p)) if p.as_char() == '$')
-}
-
 fn peek_is_hash(tokens: &mut Tokens) -> bool {
     matches!(tokens.peek(), Some(TokenTree::Punct(p)) if p.as_char() == '#')
 }

shared/yeast/doc/yeast.md

@@ -184,8 +184,8 @@ yeast::rule!(
 );
 
 // Standalone — explicit context
-let fresh = yeast::tree_builder::FreshScope::new();
-let mut ctx = BuildCtx::new(ast, &captures, &fresh);
+let mut user_ctx = ();
+let mut ctx = BuildCtx::new(ast, &captures, &mut user_ctx);
 let id = yeast::tree!(ctx,
     (assignment
         left: {ctx.capture("lhs")}
@@ -374,25 +374,6 @@ Outside a `?`, interpolating an `Option` with `#{expr}` remains a compile error.
 That is deliberate: it keeps the choice between "leave the field unset" and
 "unwrap it" explicit at every interpolation.
 
-### Fresh identifiers
-
-`(kind $name)` creates a leaf node with an auto-generated unique name. All
-occurrences of the same `$name` within one `BuildCtx` share the same value:
-
-```rust
-(block
-    parameters: (block_parameters
-        (identifier $tmp)         // generates e.g. "$tmp-0"
-    )
-    body: (block_body
-        (assignment
-            left: {pat}
-            right: (identifier $tmp)   // same "$tmp-0" value
-        )
-    )
-)
-```
-
 ### Embedded Rust expressions
 
 `{expr}` embeds a Rust expression whose value is appended to the
@@ -479,43 +460,6 @@ Mix `@` and `@@` freely in the same rule. In a Repeating phase both
 markers are equivalent (auto-translation is a no-op for repeating
 rules).
 
-## Complete example: for-loop desugaring
-
-This rule rewrites Ruby's `for pat in val do body end` into
-`val.each { |tmp| pat = tmp; body }`:
-
-```rust
-let for_rule = yeast::rule!(
-    (for
-        pattern: (_) @pat
-        value: (in (_) @val)
-        body: (do (_)* @body)
-    )
-    =>
-    (call
-        receiver: {val}
-        method: (identifier "each")
-        block: (block
-            parameters: (block_parameters
-                (identifier $tmp)
-            )
-            body: (block_body
-                (assignment
-                    left: {pat}
-                    right: (identifier $tmp)
-                )
-                {..body}
-            )
-        )
-    )
-);
-```
-
-Captures from the query (`@pat`, `@val`, `@body`) become Rust variables
-automatically: single captures bind as `Id`, repeated captures (after
-`*` or `+`) as `Vec<Id>`, and optional captures (after `?`) as
-`Option<Id>`.
-
 ## The `rule!` macro
 
 `rule!` combines a query and a transform into a single declaration.

shared/yeast/src/build.rs

@@ -1,15 +1,13 @@
 use std::collections::{BTreeMap, BTreeSet};
 
 use crate::captures::Captures;
-use crate::tree_builder::FreshScope;
 use crate::{Ast, FieldId, Id, KindId, NodeContent, Range, TranslatorHandle};
 
 /// Context for building new AST nodes during a transformation.
 ///
 /// Used by the `tree!` and `trees!` macros. Holds a mutable reference to the
-/// AST, a reference to the captures from a query match, a `FreshScope` for
-/// generating unique identifiers, and a mutable reference to a user-defined
-/// context of type `C`.
+/// AST, a reference to the captures from a query match, and a mutable reference
+/// to a user-defined context of type `C`.
 ///
 /// The user context `C` is shared across rules via the framework's driver:
 /// outer rules can write to it before recursive translation, and inner rules
@@ -32,7 +30,6 @@ use crate::{Ast, FieldId, Id, KindId, NodeContent, Range, TranslatorHandle};
 pub struct BuildCtx<'a, C: 'a = ()> {
     pub ast: &'a mut Ast,
     pub captures: &'a Captures,
-    pub fresh: &'a FreshScope,
     /// Source range of the node matched by the current rule.
     ///
     /// The `rule!` macro applies this range to locally-created result roots
@@ -54,16 +51,10 @@ pub struct BuildCtx<'a, C: 'a = ()> {
 }
 
 impl<'a, C> BuildCtx<'a, C> {
-    pub fn new(
-        ast: &'a mut Ast,
-        captures: &'a Captures,
-        fresh: &'a FreshScope,
-        user_ctx: &'a mut C,
-    ) -> Self {
+    pub fn new(ast: &'a mut Ast, captures: &'a Captures, user_ctx: &'a mut C) -> Self {
         Self {
             ast,
             captures,
-            fresh,
             source_range: None,
             user_ctx,
             translator: None,
@@ -75,14 +66,12 @@ impl<'a, C> BuildCtx<'a, C> {
     pub fn with_source_range(
         ast: &'a mut Ast,
         captures: &'a Captures,
-        fresh: &'a FreshScope,
         source_range: Option<Range>,
         user_ctx: &'a mut C,
     ) -> Self {
         Self {
             ast,
             captures,
-            fresh,
             source_range,
             user_ctx,
             translator: None,
@@ -95,15 +84,13 @@ impl<'a, C> BuildCtx<'a, C> {
     pub fn with_translator(
         ast: &'a mut Ast,
         captures: &'a Captures,
-        fresh: &'a FreshScope,
         source_range: Option<Range>,
         user_ctx: &'a mut C,
         translator: TranslatorHandle<'a, C>,
     ) -> Self {
         Self {
             ast,
             captures,
-            fresh,
             source_range,
             user_ctx,
             translator: Some(translator),
@@ -262,12 +249,6 @@ impl<'a, C> BuildCtx<'a, C> {
         let source_range = self.source_range_of(source).map(Range::empty_at_start);
         self.literal_with_source_range(kind, value, source_range)
     }
-
-    /// Create a leaf node with an auto-generated unique name.
-    pub fn fresh(&mut self, kind: &'static str, name: &str) -> Id {
-        let generated = self.fresh.resolve(name);
-        self.create_named_token_with_range(kind, generated, None)
-    }
 }
 
 impl<C: Clone> BuildCtx<'_, C> {
@@ -302,7 +283,7 @@ impl<C: Clone> BuildCtx<'_, C> {
 
     /// Run `f` with a temporary child [`BuildCtx`] whose `user_ctx` is
     /// a fresh clone of the current one, sharing everything else
-    /// (`ast`, `captures`, `fresh`, source ranges, `translator`) by re-borrow.
+    /// (`ast`, `captures`, source ranges, `translator`) by re-borrow.
     /// Nodes constructed through the child remain part of the current rule
     /// invocation. Any mutations `f` makes to the child's `user_ctx`
     /// are discarded when it returns — no restore needed, because the
@@ -334,7 +315,6 @@ impl<C: Clone> BuildCtx<'_, C> {
         let mut child = BuildCtx {
             ast: &mut *self.ast,
             captures: self.captures,
-            fresh: self.fresh,
             source_range: self.source_range,
             user_ctx: &mut child_user_ctx,
             translator: self.translator,