src/libsyntax/ast_util.rs - third_party/rust - Git at Google

 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 use ast::*;
 use ast;
 use codemap;
 use codemap::Span;
 use parse::token;
 use print::pprust;
 use ptr::P;
 use visit::{FnKind, Visitor};
 use visit;

 use std::cmp;
 use std::u32;

 pub fn path_name_i(idents: &[Ident]) -> String {
     // FIXME: Bad copies (#2543 -- same for everything else that says "bad")
     idents.iter().map(|i| i.to_string()).collect::<Vec<String>>().join("::")
 }

 pub fn is_path(e: P<Expr>) -> bool {
     match e.node { ExprPath(..) => true, _ => false }
 }


 // convert a span and an identifier to the corresponding
 // 1-segment path
 pub fn ident_to_path(s: Span, identifier: Ident) -> Path {
     ast::Path {
         span: s,
         global: false,
         segments: vec!(
             ast::PathSegment {
                 identifier: identifier,
                 parameters: ast::PathParameters::AngleBracketed(ast::AngleBracketedParameterData {
                     lifetimes: Vec::new(),
                     types: P::empty(),
                     bindings: P::empty(),
                 })
             }
         ),
     }
 }

 // If path is a single segment ident path, return that ident. Otherwise, return
 // None.
 pub fn path_to_ident(path: &Path) -> Option<Ident> {
     if path.segments.len() != 1 {
         return None;
     }

     let segment = &path.segments[0];
     if !segment.parameters.is_empty() {
         return None;
     }

     Some(segment.identifier)
 }

 pub fn ident_to_pat(id: NodeId, s: Span, i: Ident) -> P<Pat> {
     P(Pat {
         id: id,
         node: PatIdent(BindingMode::ByValue(MutImmutable), codemap::Spanned{span:s, node:i}, None),
         span: s
     })
 }

 /// Generate a "pretty" name for an `impl` from its type and trait.
 /// This is designed so that symbols of `impl`'d methods give some
 /// hint of where they came from, (previously they would all just be
 /// listed as `__extensions__::method_name::hash`, with no indication
 /// of the type).
 pub fn impl_pretty_name(trait_ref: &Option<TraitRef>, ty: Option<&Ty>) -> Ident {
     let mut pretty = match ty {
         Some(t) => pprust::ty_to_string(t),
         None => String::from("..")
     };

     match *trait_ref {
         Some(ref trait_ref) => {
             pretty.push('.');
             pretty.push_str(&pprust::path_to_string(&trait_ref.path));
         }
         None => {}
     }
     token::gensym_ident(&pretty[..])
 }

 pub fn struct_field_visibility(field: ast::StructField) -> Visibility {
     match field.node.kind {
         ast::NamedField(_, v) | ast::UnnamedField(v) => v
     }
 }

 // ______________________________________________________________________
 // Enumerating the IDs which appear in an AST

 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct IdRange {
     pub min: NodeId,
     pub max: NodeId,
 }

 impl IdRange {
     pub fn max() -> IdRange {
         IdRange {
             min: u32::MAX,
             max: u32::MIN,
         }
     }

     pub fn empty(&self) -> bool {
         self.min >= self.max
     }

     pub fn add(&mut self, id: NodeId) {
         self.min = cmp::min(self.min, id);
         self.max = cmp::max(self.max, id + 1);
     }
 }

 pub trait IdVisitingOperation {
     fn visit_id(&mut self, node_id: NodeId);
 }

 /// A visitor that applies its operation to all of the node IDs
 /// in a visitable thing.

 pub struct IdVisitor<'a, O:'a> {
     pub operation: &'a mut O,
     pub visited_outermost: bool,
 }

 impl<'a, O: IdVisitingOperation> IdVisitor<'a, O> {
     fn visit_generics_helper(&mut self, generics: &Generics) {
         for type_parameter in generics.ty_params.iter() {
             self.operation.visit_id(type_parameter.id)
         }
         for lifetime in &generics.lifetimes {
             self.operation.visit_id(lifetime.lifetime.id)
         }
     }
 }

 impl<'a, 'v, O: IdVisitingOperation> Visitor<'v> for IdVisitor<'a, O> {
     fn visit_mod(&mut self,
                  module: &Mod,
                  _: Span,
                  node_id: NodeId) {
         self.operation.visit_id(node_id);
         visit::walk_mod(self, module)
     }

     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
         self.operation.visit_id(foreign_item.id);
         visit::walk_foreign_item(self, foreign_item)
     }

     fn visit_item(&mut self, item: &Item) {
         if self.visited_outermost {
             return
         } else {
             self.visited_outermost = true
         }

         self.operation.visit_id(item.id);
         match item.node {
             ItemUse(ref view_path) => {
                 match view_path.node {
                     ViewPathSimple(_, _) |
                     ViewPathGlob(_) => {}
                     ViewPathList(_, ref paths) => {
                         for path in paths {
                             self.operation.visit_id(path.node.id())
                         }
                     }
                 }
             }
             _ => {}
         }

         visit::walk_item(self, item);

         self.visited_outermost = false
     }

     fn visit_local(&mut self, local: &Local) {
         self.operation.visit_id(local.id);
         visit::walk_local(self, local)
     }

     fn visit_block(&mut self, block: &Block) {
         self.operation.visit_id(block.id);
         visit::walk_block(self, block)
     }

     fn visit_stmt(&mut self, statement: &Stmt) {
         self.operation
             .visit_id(statement.node.id().expect("attempted to visit unexpanded stmt"));
         visit::walk_stmt(self, statement)
     }

     fn visit_pat(&mut self, pattern: &Pat) {
         self.operation.visit_id(pattern.id);
         visit::walk_pat(self, pattern)
     }

     fn visit_expr(&mut self, expression: &Expr) {
         self.operation.visit_id(expression.id);
         visit::walk_expr(self, expression)
     }

     fn visit_ty(&mut self, typ: &Ty) {
         self.operation.visit_id(typ.id);
         visit::walk_ty(self, typ)
     }

     fn visit_generics(&mut self, generics: &Generics) {
         self.visit_generics_helper(generics);
         visit::walk_generics(self, generics)
     }

     fn visit_fn(&mut self,
                 function_kind: visit::FnKind<'v>,
                 function_declaration: &'v FnDecl,
                 block: &'v Block,
                 span: Span,
                 node_id: NodeId) {
         match function_kind {
             FnKind::Method(..) if self.visited_outermost => return,
             FnKind::Method(..) => self.visited_outermost = true,
             _ => {}
         }

         self.operation.visit_id(node_id);

         match function_kind {
             FnKind::ItemFn(_, generics, _, _, _, _) => {
                 self.visit_generics_helper(generics)
             }
             FnKind::Method(_, sig, _) => {
                 self.visit_generics_helper(&sig.generics)
             }
             FnKind::Closure => {}
         }

         for argument in &function_declaration.inputs {
             self.operation.visit_id(argument.id)
         }

         visit::walk_fn(self,
                        function_kind,
                        function_declaration,
                        block,
                        span);

         if let FnKind::Method(..) = function_kind {
             self.visited_outermost = false;
         }
     }

     fn visit_struct_field(&mut self, struct_field: &StructField) {
         self.operation.visit_id(struct_field.node.id);
         visit::walk_struct_field(self, struct_field)
     }

     fn visit_variant_data(&mut self,
                         struct_def: &VariantData,
                         _: ast::Ident,
                         _: &ast::Generics,
                         _: NodeId,
                         _: Span) {
         self.operation.visit_id(struct_def.id());
         visit::walk_struct_def(self, struct_def);
     }

     fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
         self.operation.visit_id(ti.id);
         visit::walk_trait_item(self, ti);
     }

     fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
         self.operation.visit_id(ii.id);
         visit::walk_impl_item(self, ii);
     }

     fn visit_lifetime(&mut self, lifetime: &Lifetime) {
         self.operation.visit_id(lifetime.id);
     }

     fn visit_lifetime_def(&mut self, def: &LifetimeDef) {
         self.visit_lifetime(&def.lifetime);
     }

     fn visit_trait_ref(&mut self, trait_ref: &TraitRef) {
         self.operation.visit_id(trait_ref.ref_id);
         visit::walk_trait_ref(self, trait_ref);
     }
 }

 pub struct IdRangeComputingVisitor {
     pub result: IdRange,
 }

 impl IdRangeComputingVisitor {
     pub fn new() -> IdRangeComputingVisitor {
         IdRangeComputingVisitor { result: IdRange::max() }
     }

     pub fn result(&self) -> IdRange {
         self.result
     }
 }

 impl IdVisitingOperation for IdRangeComputingVisitor {
     fn visit_id(&mut self, id: NodeId) {
         self.result.add(id);
     }
 }

 /// Computes the id range for a single fn body, ignoring nested items.
 pub fn compute_id_range_for_fn_body(fk: FnKind,
                                     decl: &FnDecl,
                                     body: &Block,
                                     sp: Span,
                                     id: NodeId)
                                     -> IdRange
 {
     let mut visitor = IdRangeComputingVisitor::new();
     let mut id_visitor = IdVisitor {
         operation: &mut visitor,
         visited_outermost: false,
     };
     id_visitor.visit_fn(fk, decl, body, sp, id);
     id_visitor.operation.result
 }

 /// Returns true if the given pattern consists solely of an identifier
 /// and false otherwise.
 pub fn pat_is_ident(pat: P<ast::Pat>) -> bool {
     match pat.node {
         ast::PatIdent(..) => true,
         _ => false,
     }
 }

 // are two paths equal when compared unhygienically?
 // since I'm using this to replace ==, it seems appropriate
 // to compare the span, global, etc. fields as well.
 pub fn path_name_eq(a : &ast::Path, b : &ast::Path) -> bool {
     (a.span == b.span)
     && (a.global == b.global)
     && (segments_name_eq(&a.segments[..], &b.segments[..]))
 }

 // are two arrays of segments equal when compared unhygienically?
 pub fn segments_name_eq(a : &[ast::PathSegment], b : &[ast::PathSegment]) -> bool {
     a.len() == b.len() &&
     a.iter().zip(b).all(|(s, t)| {
         s.identifier.name == t.identifier.name &&
         // FIXME #7743: ident -> name problems in lifetime comparison?
         // can types contain idents?
         s.parameters == t.parameters
     })
 }

 #[cfg(test)]
 mod tests {
     use ast::*;
     use super::*;

     fn ident_to_segment(id: Ident) -> PathSegment {
         PathSegment {identifier: id,
                      parameters: PathParameters::none()}
     }

     #[test] fn idents_name_eq_test() {
         assert!(segments_name_eq(
             &[Ident::new(Name(3),SyntaxContext(4)), Ident::new(Name(78),SyntaxContext(82))]
                 .iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>(),
             &[Ident::new(Name(3),SyntaxContext(104)), Ident::new(Name(78),SyntaxContext(182))]
                 .iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>()));
         assert!(!segments_name_eq(
             &[Ident::new(Name(3),SyntaxContext(4)), Ident::new(Name(78),SyntaxContext(82))]
                 .iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>(),
             &[Ident::new(Name(3),SyntaxContext(104)), Ident::new(Name(77),SyntaxContext(182))]
                 .iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>()));
     }
 }
	// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	use ast::*;
	use ast;
	use codemap;
	use codemap::Span;
	use parse::token;
	use print::pprust;
	use ptr::P;
	use visit::{FnKind, Visitor};
	use visit;

	use std::cmp;
	use std::u32;

	pub fn path_name_i(idents: &[Ident]) -> String {
	// FIXME: Bad copies (#2543 -- same for everything else that says "bad")
	idents.iter().map(\|i\| i.to_string()).collect::<Vec<String>>().join("::")
	}

	pub fn is_path(e: P<Expr>) -> bool {
	match e.node { ExprPath(..) => true, _ => false }
	}


	// convert a span and an identifier to the corresponding
	// 1-segment path
	pub fn ident_to_path(s: Span, identifier: Ident) -> Path {
	ast::Path {
	span: s,
	global: false,
	segments: vec!(
	ast::PathSegment {
	identifier: identifier,
	parameters: ast::PathParameters::AngleBracketed(ast::AngleBracketedParameterData {
	lifetimes: Vec::new(),
	types: P::empty(),
	bindings: P::empty(),
	})
	}
	),
	}
	}

	// If path is a single segment ident path, return that ident. Otherwise, return
	// None.
	pub fn path_to_ident(path: &Path) -> Option<Ident> {
	if path.segments.len() != 1 {
	return None;
	}

	let segment = &path.segments[0];
	if !segment.parameters.is_empty() {
	return None;
	}

	Some(segment.identifier)
	}

	pub fn ident_to_pat(id: NodeId, s: Span, i: Ident) -> P<Pat> {
	P(Pat {
	id: id,
	node: PatIdent(BindingMode::ByValue(MutImmutable), codemap::Spanned{span:s, node:i}, None),
	span: s
	})
	}

	/// Generate a "pretty" name for an `impl` from its type and trait.
	/// This is designed so that symbols of `impl`'d methods give some
	/// hint of where they came from, (previously they would all just be
	/// listed as `__extensions__::method_name::hash`, with no indication
	/// of the type).
	pub fn impl_pretty_name(trait_ref: &Option<TraitRef>, ty: Option<&Ty>) -> Ident {
	let mut pretty = match ty {
	Some(t) => pprust::ty_to_string(t),
	None => String::from("..")
	};

	match *trait_ref {
	Some(ref trait_ref) => {
	pretty.push('.');
	pretty.push_str(&pprust::path_to_string(&trait_ref.path));
	}
	None => {}
	}
	token::gensym_ident(&pretty[..])
	}

	pub fn struct_field_visibility(field: ast::StructField) -> Visibility {
	match field.node.kind {
	ast::NamedField(_, v) \| ast::UnnamedField(v) => v
	}
	}

	// ______________________________________________________________________
	// Enumerating the IDs which appear in an AST

	#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
	pub struct IdRange {
	pub min: NodeId,
	pub max: NodeId,
	}

	impl IdRange {
	pub fn max() -> IdRange {
	IdRange {
	min: u32::MAX,
	max: u32::MIN,
	}
	}

	pub fn empty(&self) -> bool {
	self.min >= self.max
	}

	pub fn add(&mut self, id: NodeId) {
	self.min = cmp::min(self.min, id);
	self.max = cmp::max(self.max, id + 1);
	}
	}

	pub trait IdVisitingOperation {
	fn visit_id(&mut self, node_id: NodeId);
	}

	/// A visitor that applies its operation to all of the node IDs
	/// in a visitable thing.

	pub struct IdVisitor<'a, O:'a> {
	pub operation: &'a mut O,
	pub visited_outermost: bool,
	}

	impl<'a, O: IdVisitingOperation> IdVisitor<'a, O> {
	fn visit_generics_helper(&mut self, generics: &Generics) {
	for type_parameter in generics.ty_params.iter() {
	self.operation.visit_id(type_parameter.id)
	}
	for lifetime in &generics.lifetimes {
	self.operation.visit_id(lifetime.lifetime.id)
	}
	}
	}

	impl<'a, 'v, O: IdVisitingOperation> Visitor<'v> for IdVisitor<'a, O> {
	fn visit_mod(&mut self,
	module: &Mod,
	_: Span,
	node_id: NodeId) {
	self.operation.visit_id(node_id);
	visit::walk_mod(self, module)
	}

	fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
	self.operation.visit_id(foreign_item.id);
	visit::walk_foreign_item(self, foreign_item)
	}

	fn visit_item(&mut self, item: &Item) {
	if self.visited_outermost {
	return
	} else {
	self.visited_outermost = true
	}

	self.operation.visit_id(item.id);
	match item.node {
	ItemUse(ref view_path) => {
	match view_path.node {
	ViewPathSimple(_, _) \|
	ViewPathGlob(_) => {}
	ViewPathList(_, ref paths) => {
	for path in paths {
	self.operation.visit_id(path.node.id())
	}
	}
	}
	}
	_ => {}
	}

	visit::walk_item(self, item);

	self.visited_outermost = false
	}

	fn visit_local(&mut self, local: &Local) {
	self.operation.visit_id(local.id);
	visit::walk_local(self, local)
	}

	fn visit_block(&mut self, block: &Block) {
	self.operation.visit_id(block.id);
	visit::walk_block(self, block)
	}

	fn visit_stmt(&mut self, statement: &Stmt) {
	self.operation
	.visit_id(statement.node.id().expect("attempted to visit unexpanded stmt"));
	visit::walk_stmt(self, statement)
	}

	fn visit_pat(&mut self, pattern: &Pat) {
	self.operation.visit_id(pattern.id);
	visit::walk_pat(self, pattern)
	}

	fn visit_expr(&mut self, expression: &Expr) {
	self.operation.visit_id(expression.id);
	visit::walk_expr(self, expression)
	}

	fn visit_ty(&mut self, typ: &Ty) {
	self.operation.visit_id(typ.id);
	visit::walk_ty(self, typ)
	}

	fn visit_generics(&mut self, generics: &Generics) {
	self.visit_generics_helper(generics);
	visit::walk_generics(self, generics)
	}

	fn visit_fn(&mut self,
	function_kind: visit::FnKind<'v>,
	function_declaration: &'v FnDecl,
	block: &'v Block,
	span: Span,
	node_id: NodeId) {
	match function_kind {
	FnKind::Method(..) if self.visited_outermost => return,
	FnKind::Method(..) => self.visited_outermost = true,
	_ => {}
	}

	self.operation.visit_id(node_id);

	match function_kind {
	FnKind::ItemFn(_, generics, _, _, _, _) => {
	self.visit_generics_helper(generics)
	}
	FnKind::Method(_, sig, _) => {
	self.visit_generics_helper(&sig.generics)
	}
	FnKind::Closure => {}
	}

	for argument in &function_declaration.inputs {
	self.operation.visit_id(argument.id)
	}

	visit::walk_fn(self,
	function_kind,
	function_declaration,
	block,
	span);

	if let FnKind::Method(..) = function_kind {
	self.visited_outermost = false;
	}
	}

	fn visit_struct_field(&mut self, struct_field: &StructField) {
	self.operation.visit_id(struct_field.node.id);
	visit::walk_struct_field(self, struct_field)
	}

	fn visit_variant_data(&mut self,
	struct_def: &VariantData,
	_: ast::Ident,
	_: &ast::Generics,
	_: NodeId,
	_: Span) {
	self.operation.visit_id(struct_def.id());
	visit::walk_struct_def(self, struct_def);
	}

	fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
	self.operation.visit_id(ti.id);
	visit::walk_trait_item(self, ti);
	}

	fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
	self.operation.visit_id(ii.id);
	visit::walk_impl_item(self, ii);
	}

	fn visit_lifetime(&mut self, lifetime: &Lifetime) {
	self.operation.visit_id(lifetime.id);
	}

	fn visit_lifetime_def(&mut self, def: &LifetimeDef) {
	self.visit_lifetime(&def.lifetime);
	}

	fn visit_trait_ref(&mut self, trait_ref: &TraitRef) {
	self.operation.visit_id(trait_ref.ref_id);
	visit::walk_trait_ref(self, trait_ref);
	}
	}

	pub struct IdRangeComputingVisitor {
	pub result: IdRange,
	}

	impl IdRangeComputingVisitor {
	pub fn new() -> IdRangeComputingVisitor {
	IdRangeComputingVisitor { result: IdRange::max() }
	}

	pub fn result(&self) -> IdRange {
	self.result
	}
	}

	impl IdVisitingOperation for IdRangeComputingVisitor {
	fn visit_id(&mut self, id: NodeId) {
	self.result.add(id);
	}
	}

	/// Computes the id range for a single fn body, ignoring nested items.
	pub fn compute_id_range_for_fn_body(fk: FnKind,
	decl: &FnDecl,
	body: &Block,
	sp: Span,
	id: NodeId)
	-> IdRange
	{
	let mut visitor = IdRangeComputingVisitor::new();
	let mut id_visitor = IdVisitor {
	operation: &mut visitor,
	visited_outermost: false,
	};
	id_visitor.visit_fn(fk, decl, body, sp, id);
	id_visitor.operation.result
	}

	/// Returns true if the given pattern consists solely of an identifier
	/// and false otherwise.
	pub fn pat_is_ident(pat: P<ast::Pat>) -> bool {
	match pat.node {
	ast::PatIdent(..) => true,
	_ => false,
	}
	}

	// are two paths equal when compared unhygienically?
	// since I'm using this to replace ==, it seems appropriate
	// to compare the span, global, etc. fields as well.
	pub fn path_name_eq(a : &ast::Path, b : &ast::Path) -> bool {
	(a.span == b.span)
	&& (a.global == b.global)
	&& (segments_name_eq(&a.segments[..], &b.segments[..]))
	}

	// are two arrays of segments equal when compared unhygienically?
	pub fn segments_name_eq(a : &[ast::PathSegment], b : &[ast::PathSegment]) -> bool {
	a.len() == b.len() &&
	a.iter().zip(b).all(\|(s, t)\| {
	s.identifier.name == t.identifier.name &&
	// FIXME #7743: ident -> name problems in lifetime comparison?
	// can types contain idents?
	s.parameters == t.parameters
	})
	}

	#[cfg(test)]
	mod tests {
	use ast::*;
	use super::*;

	fn ident_to_segment(id: Ident) -> PathSegment {
	PathSegment {identifier: id,
	parameters: PathParameters::none()}
	}

	#[test] fn idents_name_eq_test() {
	assert!(segments_name_eq(
	&[Ident::new(Name(3),SyntaxContext(4)), Ident::new(Name(78),SyntaxContext(82))]
	.iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>(),
	&[Ident::new(Name(3),SyntaxContext(104)), Ident::new(Name(78),SyntaxContext(182))]
	.iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>()));
	assert!(!segments_name_eq(
	&[Ident::new(Name(3),SyntaxContext(4)), Ident::new(Name(78),SyntaxContext(82))]
	.iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>(),
	&[Ident::new(Name(3),SyntaxContext(104)), Ident::new(Name(77),SyntaxContext(182))]
	.iter().cloned().map(ident_to_segment).collect::<Vec<PathSegment>>()));
	}
	}