2 files changed, 48 insertions, 6 deletions

diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index e89410a76..ce750299f 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -46,6 +46,7 @@ pub use self::{
     path::{Path, PathKind},
     name::Name,
     krate::Crate,
+    macros::{MacroDef, MacroInput, MacroExpansion, MacroDatabase, ExpandMacroQuery},
     module::{Module, ModuleId, Problem, nameres::{ItemMap, PerNs, Namespace}, ModuleScope, Resolution},
     function::{Function, FnScopes},
     adt::{Struct, Enum},
diff --git a/crates/ra_hir/src/macros.rs b/crates/ra_hir/src/macros.rs
index 050b97081..ef6502524 100644
--- a/crates/ra_hir/src/macros.rs
+++ b/crates/ra_hir/src/macros.rs
@@ -1,7 +1,10 @@
 use std::sync::Arc;
 
-use ra_db::SyntaxDatabase;
-use ra_syntax::{TextRange, TextUnit, SourceFileNode, AstNode, ast};
+use ra_db::{SyntaxDatabase, LocalSyntaxPtr};
+use ra_syntax::{
+    TextRange, TextUnit, SourceFileNode, AstNode, SyntaxNode,
+    ast,
+};
 
 // Hard-coded defs for now :-(
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -12,18 +15,19 @@ pub enum MacroDef {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct MacroInput {
     // Should be token trees
-    text: String,
+    pub text: String,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct MacroExpansion {
     text: String,
     ranges_map: Vec<(TextRange, TextRange)>,
+    ptr: LocalSyntaxPtr,
 }
 
 salsa::query_group! {
 
-pub trait MacrosDatabase: SyntaxDatabase {
+pub trait MacroDatabase: SyntaxDatabase {
     fn expand_macro(def: MacroDef, input: MacroInput) -> Option<Arc<MacroExpansion>> {
         type ExpandMacroQuery;
     }
@@ -32,7 +36,7 @@ pub trait MacrosDatabase: SyntaxDatabase {
 }
 
 fn expand_macro(
-    _db: &impl MacrosDatabase,
+    _db: &impl MacroDatabase,
     def: MacroDef,
     input: MacroInput,
 ) -> Option<Arc<MacroExpansion>> {
@@ -50,8 +54,45 @@ fn expand_macro(
     let file = SourceFileNode::parse(&text);
     let match_expr = file.syntax().descendants().find_map(ast::MatchExpr::cast)?;
     let match_arg = match_expr.expr()?;
+    let ptr = LocalSyntaxPtr::new(match_arg.syntax());
     let src_range = TextRange::offset_len(0.into(), TextUnit::of_str(&input.text));
     let ranges_map = vec![(src_range, match_arg.syntax().range())];
-    let res = MacroExpansion { text, ranges_map };
+    let res = MacroExpansion {
+        text,
+        ranges_map,
+        ptr,
+    };
     Some(Arc::new(res))
 }
+
+impl MacroExpansion {
+    pub fn file(&self) -> SourceFileNode {
+        SourceFileNode::parse(&self.text)
+    }
+
+    pub fn syntax(&self) -> SyntaxNode {
+        self.ptr.resolve(&self.file())
+    }
+    pub fn map_range_back(&self, tgt_range: TextRange) -> Option<TextRange> {
+        for (s_range, t_range) in self.ranges_map.iter() {
+            if tgt_range.is_subrange(&t_range) {
+                let tgt_at_zero_range = tgt_range - tgt_range.start();
+                let tgt_range_offset = tgt_range.start() - t_range.start();
+                let src_range = tgt_at_zero_range + tgt_range_offset + s_range.start();
+                return Some(src_range);
+            }
+        }
+        None
+    }
+    pub fn map_range_forward(&self, src_range: TextRange) -> Option<TextRange> {
+        for (s_range, t_range) in self.ranges_map.iter() {
+            if src_range.is_subrange(&s_range) {
+                let src_at_zero_range = src_range - src_range.start();
+                let src_range_offset = src_range.start() - s_range.start();
+                let src_range = src_at_zero_range + src_range_offset + t_range.start();
+                return Some(src_range);
+            }
+        }
+        None
+    }
+}