292 lines
10 KiB
Rust
292 lines
10 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use attr::{AttrMetaMethods, HasAttrs};
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use errors::Handler;
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use feature_gate::GatedCfgAttr;
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use fold::Folder;
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use {ast, fold, attr};
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use codemap::{Spanned, respan};
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use ptr::P;
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use util::small_vector::SmallVector;
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pub trait CfgFolder: fold::Folder {
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// Check if a node with the given attributes is in this configuration.
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fn in_cfg(&mut self, attrs: &[ast::Attribute]) -> bool;
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// Update a node before checking if it is in this configuration (used to implement `cfg_attr`).
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fn process_attrs<T: HasAttrs>(&mut self, node: T) -> T { node }
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// Visit attributes on expression and statements (but not attributes on items in blocks).
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fn visit_stmt_or_expr_attrs(&mut self, _attrs: &[ast::Attribute]) {}
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// Visit unremovable (non-optional) expressions -- c.f. `fold_expr` vs `fold_opt_expr`.
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fn visit_unremovable_expr(&mut self, _expr: &ast::Expr) {}
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fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
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let node = self.process_attrs(node);
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if self.in_cfg(node.attrs()) { Some(node) } else { None }
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}
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}
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/// A folder that strips out items that do not belong in the current
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/// configuration.
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pub struct StripUnconfigured<'a> {
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diag: CfgDiagReal<'a, 'a>,
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config: &'a ast::CrateConfig,
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}
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impl<'a> StripUnconfigured<'a> {
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pub fn new(config: &'a ast::CrateConfig,
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diagnostic: &'a Handler,
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feature_gated_cfgs: &'a mut Vec<GatedCfgAttr>)
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-> Self {
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StripUnconfigured {
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config: config,
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diag: CfgDiagReal { diag: diagnostic, feature_gated_cfgs: feature_gated_cfgs },
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}
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}
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fn process_cfg_attr(&mut self, attr: ast::Attribute) -> Option<ast::Attribute> {
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if !attr.check_name("cfg_attr") {
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return Some(attr);
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}
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let attr_list = match attr.meta_item_list() {
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Some(attr_list) => attr_list,
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None => {
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let msg = "expected `#[cfg_attr(<cfg pattern>, <attr>)]`";
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self.diag.diag.span_err(attr.span, msg);
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return None;
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}
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};
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let (cfg, mi) = match (attr_list.len(), attr_list.get(0), attr_list.get(1)) {
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(2, Some(cfg), Some(mi)) => (cfg, mi),
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_ => {
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let msg = "expected `#[cfg_attr(<cfg pattern>, <attr>)]`";
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self.diag.diag.span_err(attr.span, msg);
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return None;
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}
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};
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if attr::cfg_matches(self.config, &cfg, &mut self.diag) {
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Some(respan(mi.span, ast::Attribute_ {
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id: attr::mk_attr_id(),
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style: attr.node.style,
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value: mi.clone(),
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is_sugared_doc: false,
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}))
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} else {
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None
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}
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}
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}
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impl<'a> CfgFolder for StripUnconfigured<'a> {
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// Determine if an item should be translated in the current crate
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// configuration based on the item's attributes
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fn in_cfg(&mut self, attrs: &[ast::Attribute]) -> bool {
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attrs.iter().all(|attr| {
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let mis = match attr.node.value.node {
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ast::MetaItemKind::List(_, ref mis) if is_cfg(&attr) => mis,
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_ => return true
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};
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if mis.len() != 1 {
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self.diag.emit_error(|diagnostic| {
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diagnostic.span_err(attr.span, "expected 1 cfg-pattern");
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});
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return true;
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}
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attr::cfg_matches(self.config, &mis[0], &mut self.diag)
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})
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}
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fn process_attrs<T: HasAttrs>(&mut self, node: T) -> T {
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node.map_attrs(|attrs| {
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attrs.into_iter().filter_map(|attr| self.process_cfg_attr(attr)).collect()
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})
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}
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fn visit_stmt_or_expr_attrs(&mut self, attrs: &[ast::Attribute]) {
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// flag the offending attributes
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for attr in attrs.iter() {
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self.diag.feature_gated_cfgs.push(GatedCfgAttr::GatedAttr(attr.span));
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}
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}
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fn visit_unremovable_expr(&mut self, expr: &ast::Expr) {
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if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(a)) {
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let msg = "removing an expression is not supported in this position";
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self.diag.diag.span_err(attr.span, msg);
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}
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}
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}
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// Support conditional compilation by transforming the AST, stripping out
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// any items that do not belong in the current configuration
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pub fn strip_unconfigured_items(diagnostic: &Handler, krate: ast::Crate,
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feature_gated_cfgs: &mut Vec<GatedCfgAttr>)
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-> ast::Crate
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{
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let config = &krate.config.clone();
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StripUnconfigured::new(config, diagnostic, feature_gated_cfgs).fold_crate(krate)
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}
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impl<T: CfgFolder> fold::Folder for T {
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fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
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ast::ForeignMod {
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abi: foreign_mod.abi,
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items: foreign_mod.items.into_iter().filter_map(|item| {
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self.configure(item).map(|item| fold::noop_fold_foreign_item(item, self))
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}).collect(),
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}
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}
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fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
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let fold_struct = |this: &mut Self, vdata| match vdata {
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ast::VariantData::Struct(fields, id) => {
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let fields = fields.into_iter().filter_map(|field| this.configure(field));
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ast::VariantData::Struct(fields.collect(), id)
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}
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ast::VariantData::Tuple(fields, id) => {
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let fields = fields.into_iter().filter_map(|field| this.configure(field));
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ast::VariantData::Tuple(fields.collect(), id)
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}
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ast::VariantData::Unit(id) => ast::VariantData::Unit(id)
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};
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let item = match item {
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ast::ItemKind::Struct(def, generics) => {
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ast::ItemKind::Struct(fold_struct(self, def), generics)
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}
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ast::ItemKind::Enum(def, generics) => {
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let variants = def.variants.into_iter().filter_map(|v| {
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self.configure(v).map(|v| {
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Spanned {
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node: ast::Variant_ {
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name: v.node.name,
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attrs: v.node.attrs,
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data: fold_struct(self, v.node.data),
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disr_expr: v.node.disr_expr,
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},
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span: v.span
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}
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})
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});
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ast::ItemKind::Enum(ast::EnumDef {
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variants: variants.collect(),
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}, generics)
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}
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item => item,
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};
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fold::noop_fold_item_kind(item, self)
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}
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fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
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self.visit_stmt_or_expr_attrs(expr.attrs());
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// If an expr is valid to cfg away it will have been removed by the
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// outer stmt or expression folder before descending in here.
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// Anything else is always required, and thus has to error out
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// in case of a cfg attr.
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//
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// NB: This is intentionally not part of the fold_expr() function
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// in order for fold_opt_expr() to be able to avoid this check
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self.visit_unremovable_expr(&expr);
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let expr = self.process_attrs(expr);
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fold_expr(self, expr)
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}
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fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
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self.configure(expr).map(|expr| fold_expr(self, expr))
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}
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fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
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let is_item = match stmt.node {
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ast::StmtKind::Decl(ref decl, _) => match decl.node {
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ast::DeclKind::Item(_) => true,
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_ => false,
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},
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_ => false,
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};
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// avoid calling `visit_stmt_or_expr_attrs` on items
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if !is_item {
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self.visit_stmt_or_expr_attrs(stmt.attrs());
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}
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self.configure(stmt).map(|stmt| fold::noop_fold_stmt(stmt, self))
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.unwrap_or(SmallVector::zero())
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}
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fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
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fold::noop_fold_mac(mac, self)
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}
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fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
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self.configure(item).map(|item| fold::noop_fold_item(item, self))
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.unwrap_or(SmallVector::zero())
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}
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fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
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self.configure(item).map(|item| fold::noop_fold_impl_item(item, self))
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.unwrap_or(SmallVector::zero())
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}
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fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
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self.configure(item).map(|item| fold::noop_fold_trait_item(item, self))
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.unwrap_or(SmallVector::zero())
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}
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}
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fn fold_expr<F: CfgFolder>(folder: &mut F, expr: P<ast::Expr>) -> P<ast::Expr> {
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expr.map(|ast::Expr {id, span, node, attrs}| {
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fold::noop_fold_expr(ast::Expr {
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id: id,
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node: match node {
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ast::ExprKind::Match(m, arms) => {
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ast::ExprKind::Match(m, arms.into_iter()
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.filter_map(|a| folder.configure(a))
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.collect())
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}
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_ => node
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},
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span: span,
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attrs: attrs,
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}, folder)
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})
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}
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fn is_cfg(attr: &ast::Attribute) -> bool {
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attr.check_name("cfg")
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}
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pub trait CfgDiag {
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fn emit_error<F>(&mut self, f: F) where F: FnMut(&Handler);
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fn flag_gated<F>(&mut self, f: F) where F: FnMut(&mut Vec<GatedCfgAttr>);
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}
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pub struct CfgDiagReal<'a, 'b> {
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pub diag: &'a Handler,
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pub feature_gated_cfgs: &'b mut Vec<GatedCfgAttr>,
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}
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impl<'a, 'b> CfgDiag for CfgDiagReal<'a, 'b> {
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fn emit_error<F>(&mut self, mut f: F) where F: FnMut(&Handler) {
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f(self.diag)
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}
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fn flag_gated<F>(&mut self, mut f: F) where F: FnMut(&mut Vec<GatedCfgAttr>) {
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f(self.feature_gated_cfgs)
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}
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}
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