Introduce ra_cfg to parse and evaluate CfgExpr

10 files changed, 301 insertions, 27 deletions

diff --git a/crates/ra_cfg/Cargo.toml b/crates/ra_cfg/Cargo.toml
new file mode 100644
index 000000000..b28affc3a
--- /dev/null
+++ b/crates/ra_cfg/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+edition = "2018"
+name = "ra_cfg"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+
+[dependencies]
+rustc-hash = "1.0.1"
+
+ra_syntax = { path = "../ra_syntax" }
+tt = { path = "../ra_tt", package = "ra_tt" }
+
+[dev-dependencies]
+mbe = { path = "../ra_mbe", package = "ra_mbe" }
diff --git a/crates/ra_cfg/src/cfg_expr.rs b/crates/ra_cfg/src/cfg_expr.rs
new file mode 100644
index 000000000..efeadf462
--- /dev/null
+++ b/crates/ra_cfg/src/cfg_expr.rs
@@ -0,0 +1,128 @@
+use std::slice::Iter as SliceIter;
+
+use ra_syntax::SmolStr;
+use tt::{Leaf, Subtree, TokenTree};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum CfgExpr {
+    Invalid,
+    Atom(SmolStr),
+    KeyValue { key: SmolStr, value: SmolStr },
+    All(Vec<CfgExpr>),
+    Any(Vec<CfgExpr>),
+    Not(Box<CfgExpr>),
+}
+
+impl CfgExpr {
+    /// Fold the cfg by querying all basic `Atom` and `KeyValue` predicates.
+    pub fn fold(&self, query: &impl Fn(&SmolStr, Option<&SmolStr>) -> bool) -> Option<bool> {
+        match self {
+            CfgExpr::Invalid => None,
+            CfgExpr::Atom(name) => Some(query(name, None)),
+            CfgExpr::KeyValue { key, value } => Some(query(key, Some(value))),
+            CfgExpr::All(preds) => {
+                preds.iter().try_fold(true, |s, pred| Some(s && pred.fold(query)?))
+            }
+            CfgExpr::Any(preds) => {
+                preds.iter().try_fold(false, |s, pred| Some(s || pred.fold(query)?))
+            }
+            CfgExpr::Not(pred) => pred.fold(query).map(|s| !s),
+        }
+    }
+}
+
+pub fn parse_cfg(tt: &Subtree) -> CfgExpr {
+    next_cfg_expr(&mut tt.token_trees.iter()).unwrap_or(CfgExpr::Invalid)
+}
+
+fn next_cfg_expr(it: &mut SliceIter<tt::TokenTree>) -> Option<CfgExpr> {
+    let name = match it.next() {
+        None => return None,
+        Some(TokenTree::Leaf(Leaf::Ident(ident))) => ident.text.clone(),
+        Some(_) => return Some(CfgExpr::Invalid),
+    };
+
+    // Peek
+    let ret = match it.as_slice().first() {
+        Some(TokenTree::Leaf(Leaf::Punct(punct))) if punct.char == '=' => {
+            match it.as_slice().get(1) {
+                Some(TokenTree::Leaf(Leaf::Literal(literal))) => {
+                    it.next();
+                    it.next();
+                    // FIXME: escape? raw string?
+                    let value =
+                        SmolStr::new(literal.text.trim_start_matches('"').trim_end_matches('"'));
+                    CfgExpr::KeyValue { key: name, value }
+                }
+                _ => return Some(CfgExpr::Invalid),
+            }
+        }
+        Some(TokenTree::Subtree(subtree)) => {
+            it.next();
+            let mut sub_it = subtree.token_trees.iter();
+            let mut subs = std::iter::from_fn(|| next_cfg_expr(&mut sub_it)).collect();
+            match name.as_str() {
+                "all" => CfgExpr::All(subs),
+                "any" => CfgExpr::Any(subs),
+                "not" => CfgExpr::Not(Box::new(subs.pop().unwrap_or(CfgExpr::Invalid))),
+                _ => CfgExpr::Invalid,
+            }
+        }
+        _ => CfgExpr::Atom(name),
+    };
+
+    // Eat comma separator
+    if let Some(TokenTree::Leaf(Leaf::Punct(punct))) = it.as_slice().first() {
+        if punct.char == ',' {
+            it.next();
+        }
+    }
+    Some(ret)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use mbe::ast_to_token_tree;
+    use ra_syntax::ast::{self, AstNode};
+
+    fn assert_parse_result(input: &str, expected: CfgExpr) {
+        let source_file = ast::SourceFile::parse(input).ok().unwrap();
+        let tt = source_file.syntax().descendants().find_map(ast::TokenTree::cast).unwrap();
+        let (tt, _) = ast_to_token_tree(&tt).unwrap();
+        assert_eq!(parse_cfg(&tt), expected);
+    }
+
+    #[test]
+    fn test_cfg_expr_parser() {
+        assert_parse_result("#![cfg(foo)]", CfgExpr::Atom("foo".into()));
+        assert_parse_result("#![cfg(foo,)]", CfgExpr::Atom("foo".into()));
+        assert_parse_result(
+            "#![cfg(not(foo))]",
+            CfgExpr::Not(Box::new(CfgExpr::Atom("foo".into()))),
+        );
+        assert_parse_result("#![cfg(foo(bar))]", CfgExpr::Invalid);
+
+        // Only take the first
+        assert_parse_result(r#"#![cfg(foo, bar = "baz")]"#, CfgExpr::Atom("foo".into()));
+
+        assert_parse_result(
+            r#"#![cfg(all(foo, bar = "baz"))]"#,
+            CfgExpr::All(vec![
+                CfgExpr::Atom("foo".into()),
+                CfgExpr::KeyValue { key: "bar".into(), value: "baz".into() },
+            ]),
+        );
+
+        assert_parse_result(
+            r#"#![cfg(any(not(), all(), , bar = "baz",))]"#,
+            CfgExpr::Any(vec![
+                CfgExpr::Not(Box::new(CfgExpr::Invalid)),
+                CfgExpr::All(vec![]),
+                CfgExpr::Invalid,
+                CfgExpr::KeyValue { key: "bar".into(), value: "baz".into() },
+            ]),
+        );
+    }
+}
diff --git a/crates/ra_cfg/src/lib.rs b/crates/ra_cfg/src/lib.rs
new file mode 100644
index 000000000..fa5822d8a
--- /dev/null
+++ b/crates/ra_cfg/src/lib.rs
@@ -0,0 +1,43 @@
+//! ra_cfg defines conditional compiling options, `cfg` attibute parser and evaluator
+use ra_syntax::SmolStr;
+use rustc_hash::{FxHashMap, FxHashSet};
+
+mod cfg_expr;
+
+pub use cfg_expr::{parse_cfg, CfgExpr};
+
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct CfgOptions {
+    atoms: FxHashSet<SmolStr>,
+    features: FxHashSet<SmolStr>,
+    options: FxHashMap<SmolStr, SmolStr>,
+}
+
+impl CfgOptions {
+    pub fn check(&self, cfg: &CfgExpr) -> Option<bool> {
+        cfg.fold(&|key, value| match value {
+            None => self.atoms.contains(key),
+            Some(value) if key == "feature" => self.features.contains(value),
+            Some(value) => self.options.get(key).map_or(false, |v| v == value),
+        })
+    }
+
+    pub fn is_cfg_enabled(&self, attr: &tt::Subtree) -> Option<bool> {
+        self.check(&parse_cfg(attr))
+    }
+
+    pub fn atom(mut self, name: SmolStr) -> CfgOptions {
+        self.atoms.insert(name);
+        self
+    }
+
+    pub fn feature(mut self, name: SmolStr) -> CfgOptions {
+        self.features.insert(name);
+        self
+    }
+
+    pub fn option(mut self, key: SmolStr, value: SmolStr) -> CfgOptions {
+        self.options.insert(key, value);
+        self
+    }
+}
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 2fac07bc5..c141f1a88 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -10,4 +10,5 @@ relative-path = "0.4.0"
 rustc-hash = "1.0"
 
 ra_syntax = { path = "../ra_syntax" }
+ra_cfg = { path = "../ra_cfg" }
 ra_prof = { path = "../ra_prof" }
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index 52f892891..5fd6edd78 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -9,6 +9,7 @@
 use relative_path::{RelativePath, RelativePathBuf};
 use rustc_hash::FxHashMap;
 
+use ra_cfg::CfgOptions;
 use ra_syntax::SmolStr;
 use rustc_hash::FxHashSet;
 
@@ -109,11 +110,13 @@ struct CrateData {
     file_id: FileId,
     edition: Edition,
     dependencies: Vec<Dependency>,
+    cfg_options: CfgOptions,
 }
 
 impl CrateData {
     fn new(file_id: FileId, edition: Edition) -> CrateData {
-        CrateData { file_id, edition, dependencies: Vec::new() }
+        // FIXME: cfg options
+        CrateData { file_id, edition, dependencies: Vec::new(), cfg_options: CfgOptions::default() }
     }
 
     fn add_dep(&mut self, name: SmolStr, crate_id: CrateId) {
@@ -141,6 +144,10 @@ impl CrateGraph {
         crate_id
     }
 
+    pub fn cfg_options(&self, crate_id: CrateId) -> &CfgOptions {
+        &self.arena[&crate_id].cfg_options
+    }
+
     pub fn add_dep(
         &mut self,
         from: CrateId,
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index d9bed4dda..cc117f84d 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -15,6 +15,7 @@ once_cell = "1.0.1"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_arena = { path = "../ra_arena" }
+ra_cfg = { path = "../ra_cfg" }
 ra_db = { path = "../ra_db" }
 mbe = { path = "../ra_mbe", package = "ra_mbe" }
 tt = { path = "../ra_tt", package = "ra_tt" }
diff --git a/crates/ra_hir/src/attr.rs b/crates/ra_hir/src/attr.rs
new file mode 100644
index 000000000..19be6de32
--- /dev/null
+++ b/crates/ra_hir/src/attr.rs
@@ -0,0 +1,58 @@
+use mbe::ast_to_token_tree;
+use ra_syntax::{
+    ast::{self, AstNode},
+    SmolStr,
+};
+use tt::Subtree;
+
+use crate::{db::AstDatabase, path::Path, Source};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct Attr {
+    pub(crate) path: Path,
+    pub(crate) input: Option<AttrInput>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AttrInput {
+    Literal(SmolStr),
+    TokenTree(Subtree),
+}
+
+impl Attr {
+    pub(crate) fn from_src(
+        Source { file_id, ast }: Source<ast::Attr>,
+        db: &impl AstDatabase,
+    ) -> Option<Attr> {
+        let path = Path::from_src(Source { file_id, ast: ast.path()? }, db)?;
+        let input = match ast.input() {
+            None => None,
+            Some(ast::AttrInput::Literal(lit)) => {
+                // FIXME: escape? raw string?
+                let value = lit.syntax().first_token()?.text().trim_matches('"').into();
+                Some(AttrInput::Literal(value))
+            }
+            Some(ast::AttrInput::TokenTree(tt)) => {
+                Some(AttrInput::TokenTree(ast_to_token_tree(&tt)?.0))
+            }
+        };
+
+        Some(Attr { path, input })
+    }
+
+    pub(crate) fn is_simple_atom(&self, name: &str) -> bool {
+        // FIXME: Avoid cloning
+        self.path.as_ident().map_or(false, |s| s.to_string() == name)
+    }
+
+    pub(crate) fn as_cfg(&self) -> Option<&Subtree> {
+        if self.is_simple_atom("cfg") {
+            match &self.input {
+                Some(AttrInput::TokenTree(subtree)) => Some(subtree),
+                _ => None,
+            }
+        } else {
+            None
+        }
+    }
+}
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 00031deba..4340e9d34 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -44,6 +44,7 @@ mod traits;
 mod type_alias;
 mod type_ref;
 mod ty;
+mod attr;
 mod impl_block;
 mod expr;
 mod lang_item;
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index 40e56dfe0..f0e790e4c 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -1,11 +1,13 @@
 //! FIXME: write short doc here
 
+use ra_cfg::CfgOptions;
 use ra_db::FileId;
 use ra_syntax::{ast, SmolStr};
 use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 
 use crate::{
+    attr::Attr,
     db::DefDatabase,
     ids::{AstItemDef, LocationCtx, MacroCallId, MacroCallLoc, MacroDefId, MacroFileKind},
     name::MACRO_RULES,
@@ -35,6 +37,9 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         }
     }
 
+    let crate_graph = db.crate_graph();
+    let cfg_options = crate_graph.cfg_options(def_map.krate().crate_id());
+
     let mut collector = DefCollector {
         db,
         def_map,
@@ -42,6 +47,7 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         unresolved_imports: Vec::new(),
         unexpanded_macros: Vec::new(),
         macro_stack_monitor: MacroStackMonitor::default(),
+        cfg_options,
     };
     collector.collect();
     collector.finish()
@@ -76,8 +82,8 @@ impl MacroStackMonitor {
 }
 
 /// Walks the tree of module recursively
-struct DefCollector<DB> {
-    db: DB,
+struct DefCollector<'a, DB> {
+    db: &'a DB,
     def_map: CrateDefMap,
     glob_imports: FxHashMap<CrateModuleId, Vec<(CrateModuleId, raw::ImportId)>>,
     unresolved_imports: Vec<(CrateModuleId, raw::ImportId, raw::ImportData)>,
@@ -86,9 +92,11 @@ struct DefCollector<DB> {
     /// Some macro use `$tt:tt which mean we have to handle the macro perfectly
     /// To prevent stack overflow, we add a deep counter here for prevent that.
     macro_stack_monitor: MacroStackMonitor,
+
+    cfg_options: &'a CfgOptions,
 }
 
-impl<'a, DB> DefCollector<&'a DB>
+impl<DB> DefCollector<'_, DB>
 where
     DB: DefDatabase,
 {
@@ -506,7 +514,7 @@ struct ModCollector<'a, D> {
     parent_module: Option<ParentModule<'a>>,
 }
 
-impl<DB> ModCollector<'_, &'_ mut DefCollector<&'_ DB>>
+impl<DB> ModCollector<'_, &'_ mut DefCollector<'_, DB>>
 where
     DB: DefDatabase,
 {
@@ -523,23 +531,27 @@ where
         // `#[macro_use] extern crate` is hoisted to imports macros before collecting
         // any other items.
         for item in items {
-            if let raw::RawItemKind::Import(import_id) = item.kind {
-                let import = self.raw_items[import_id].clone();
-                if import.is_extern_crate && import.is_macro_use {
-                    self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+            if self.is_cfg_enabled(&item.attrs) {
+                if let raw::RawItemKind::Import(import_id) = item.kind {
+                    let import = self.raw_items[import_id].clone();
+                    if import.is_extern_crate && import.is_macro_use {
+                        self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+                    }
                 }
             }
         }
 
         for item in items {
-            match item.kind {
-                raw::RawItemKind::Module(m) => self.collect_module(&self.raw_items[m]),
-                raw::RawItemKind::Import(import_id) => self
-                    .def_collector
-                    .unresolved_imports
-                    .push((self.module_id, import_id, self.raw_items[import_id].clone())),
-                raw::RawItemKind::Def(def) => self.define_def(&self.raw_items[def]),
-                raw::RawItemKind::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+            if self.is_cfg_enabled(&item.attrs) {
+                match item.kind {
+                    raw::RawItemKind::Module(m) => self.collect_module(&self.raw_items[m]),
+                    raw::RawItemKind::Import(import_id) => self
+                        .def_collector
+                        .unresolved_imports
+                        .push((self.module_id, import_id, self.raw_items[import_id].clone())),
+                    raw::RawItemKind::Def(def) => self.define_def(&self.raw_items[def]),
+                    raw::RawItemKind::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+                }
             }
         }
     }
@@ -702,6 +714,13 @@ where
             self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_);
         }
     }
+
+    fn is_cfg_enabled(&self, attrs: &[Attr]) -> bool {
+        attrs
+            .iter()
+            .flat_map(|attr| attr.as_cfg())
+            .all(|cfg| self.def_collector.cfg_options.is_cfg_enabled(cfg).unwrap_or(true))
+    }
 }
 
 fn is_macro_rules(path: &Path) -> bool {
@@ -729,6 +748,7 @@ mod tests {
             unresolved_imports: Vec::new(),
             unexpanded_macros: Vec::new(),
             macro_stack_monitor: monitor,
+            cfg_options: &CfgOptions::default(),
         };
         collector.collect();
         collector.finish()
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index cacbcb517..ff079bcf1 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir/src/nameres/raw.rs
@@ -2,7 +2,6 @@
 
 use std::{ops::Index, sync::Arc};
 
-use mbe::ast_to_token_tree;
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
 use ra_syntax::{
     ast::{self, AttrsOwner, NameOwner},
@@ -11,6 +10,7 @@ use ra_syntax::{
 use test_utils::tested_by;
 
 use crate::{
+    attr::Attr,
     db::{AstDatabase, DefDatabase},
     AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path, Source,
 };
@@ -29,8 +29,6 @@ pub struct RawItems {
     items: Vec<RawItem>,
 }
 
-type Attrs = Arc<[tt::Subtree]>;
-
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct ImportSourceMap {
     map: ArenaMap<ImportId, ImportSourcePtr>,
@@ -124,7 +122,7 @@ impl Index<Macro> for RawItems {
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub(super) struct RawItem {
-    pub(super) attrs: Attrs,
+    pub(super) attrs: Arc<[Attr]>,
     pub(super) kind: RawItemKind,
 }
 
@@ -285,6 +283,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         let attrs = self.parse_attrs(&module);
 
         let ast_id = self.source_ast_id_map.ast_id(&module);
+        // FIXME: cfg_attr
         let is_macro_use = module.has_atom_attr("macro_use");
         if module.has_semi() {
             let attr_path = extract_mod_path_attribute(&module);
@@ -315,6 +314,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
     }
 
     fn add_use_item(&mut self, current_module: Option<Module>, use_item: ast::UseItem) {
+        // FIXME: cfg_attr
         let is_prelude = use_item.has_atom_attr("prelude_import");
         let attrs = self.parse_attrs(&use_item);
 
@@ -349,6 +349,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
             let path = Path::from_name_ref(&name_ref);
             let alias = extern_crate.alias().and_then(|a| a.name()).map(|it| it.as_name());
             let attrs = self.parse_attrs(&extern_crate);
+            // FIXME: cfg_attr
             let is_macro_use = extern_crate.has_atom_attr("macro_use");
             let import_data = ImportData {
                 path,
@@ -368,6 +369,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
     }
 
     fn add_macro(&mut self, current_module: Option<Module>, m: ast::MacroCall) {
+        let attrs = self.parse_attrs(&m);
         let path = match m
             .path()
             .and_then(|path| Path::from_src(Source { ast: path, file_id: self.file_id }, self.db))
@@ -378,6 +380,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
 
         let name = m.name().map(|it| it.as_name());
         let ast_id = self.source_ast_id_map.ast_id(&m);
+        // FIXME: cfg_attr
         let export = m.attrs().filter_map(|x| x.simple_name()).any(|name| name == "macro_export");
 
         let m = self.raw_items.macros.alloc(MacroData { ast_id, path, name, export });
@@ -387,7 +390,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
     fn push_import(
         &mut self,
         current_module: Option<Module>,
-        attrs: Attrs,
+        attrs: Arc<[Attr]>,
         data: ImportData,
         source: ImportSourcePtr,
     ) {
@@ -396,7 +399,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         self.push_item(current_module, attrs, RawItemKind::Import(import))
     }
 
-    fn push_item(&mut self, current_module: Option<Module>, attrs: Attrs, kind: RawItemKind) {
+    fn push_item(&mut self, current_module: Option<Module>, attrs: Arc<[Attr]>, kind: RawItemKind) {
         match current_module {
             Some(module) => match &mut self.raw_items.modules[module] {
                 ModuleData::Definition { items, .. } => items,
@@ -407,11 +410,9 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         .push(RawItem { attrs, kind })
     }
 
-    fn parse_attrs(&self, item: &impl ast::AttrsOwner) -> Attrs {
+    fn parse_attrs(&self, item: &impl ast::AttrsOwner) -> Arc<[Attr]> {
         item.attrs()
-            .flat_map(|attr| attr.value())
-            .flat_map(|tt| ast_to_token_tree(&tt))
-            .map(|(tt, _)| tt)
+            .flat_map(|ast| Attr::from_src(Source { ast, file_id: self.file_id }, self.db))
             .collect()
     }
 }