Support if-let in scopes

2 files changed, 98 insertions, 16 deletions

diff --git a/crates/libeditor/src/completion.rs b/crates/libeditor/src/completion.rs
index ec9388ee3..69c039e83 100644
--- a/crates/libeditor/src/completion.rs
+++ b/crates/libeditor/src/completion.rs
@@ -1,4 +1,7 @@
-use std::collections::HashMap;
+use std::{
+    fmt,
+    collections::HashMap,
+};
 
 use libsyntax2::{
     File, TextUnit, AstNode, SyntaxNodeRef, SyntaxNode, SmolStr,
@@ -49,33 +52,89 @@ fn compute_scopes(fn_def: ast::FnDef) -> FnScopes {
         .filter_map(|it| it.pat())
         .for_each(|it| scopes.add_bindings(root, it));
 
-    let mut scope = root;
     if let Some(body) = fn_def.body() {
-        for stmt in body.statements() {
-            match stmt {
-                ast::Stmt::LetStmt(stmt) => {
-                    scope = scopes.new_scope(scope);
-                    if let Some(pat) = stmt.pat() {
-                        scopes.add_bindings(scope, pat);
-                    }
-                    if let Some(expr) = stmt.initializer() {
-                        scopes.set_scope(expr.syntax(), scope)
-                    }
+        compute_block_scopes(body, &mut scopes, root)
+    }
+    scopes
+}
+
+fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
+    for stmt in block.statements() {
+        match stmt {
+            ast::Stmt::LetStmt(stmt) => {
+                scope = scopes.new_scope(scope);
+                if let Some(pat) = stmt.pat() {
+                    scopes.add_bindings(scope, pat);
                 }
-                ast::Stmt::ExprStmt(expr) => {
+                if let Some(expr) = stmt.initializer() {
                     scopes.set_scope(expr.syntax(), scope)
                 }
             }
+            ast::Stmt::ExprStmt(expr_stmt) => {
+                if let Some(expr) = expr_stmt.expr() {
+                    scopes.set_scope(expr.syntax(), scope);
+                    compute_expr_scopes(expr, scopes, scope);
+                }
+            }
+        }
+    }
+    if let Some(expr) = block.expr() {
+        scopes.set_scope(expr.syntax(), scope);
+        compute_expr_scopes(expr, scopes, scope);
+    }
+}
+
+fn compute_expr_scopes(expr: ast::Expr, scopes: &mut FnScopes, scope: ScopeId) {
+    match expr {
+        ast::Expr::IfExpr(e) => {
+            let cond_scope = e.condition().and_then(|cond| {
+                compute_cond_scopes(cond, scopes, scope)
+            });
+            if let Some(block) = e.then_branch() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+            if let Some(block) = e.else_branch() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        },
+        ast::Expr::WhileExpr(e) => {
+            let cond_scope = e.condition().and_then(|cond| {
+                compute_cond_scopes(cond, scopes, scope)
+            });
+            if let Some(block) = e.body() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+        },
+        ast::Expr::BlockExpr(e) => {
+            if let Some(block) = e.block() {
+                compute_block_scopes(block, scopes, scope);
+            }
         }
-        if let Some(expr) = body.expr() {
-            scopes.set_scope(expr.syntax(), scope)
+        // ForExpr(e) => TODO,
+        _ => {
+            expr.syntax().children()
+                .filter_map(ast::Expr::cast)
+                .for_each(|expr| compute_expr_scopes(expr, scopes, scope))
+        }
+    };
+
+    fn compute_cond_scopes(cond: ast::Condition, scopes: &mut FnScopes, scope: ScopeId) -> Option<ScopeId> {
+        if let Some(expr) = cond.expr() {
+            compute_expr_scopes(expr, scopes, scope);
+        }
+        if let Some(pat) = cond.pat() {
+            let s = scopes.new_scope(scope);
+            scopes.add_bindings(s, pat);
+            Some(s)
+        } else {
+            None
         }
     }
-    scopes
 }
 
 type ScopeId = usize;
 
+#[derive(Debug)]
 struct FnScopes {
     scopes: Vec<ScopeData>,
     scope_for: HashMap<SyntaxNode, ScopeId>,
@@ -120,6 +179,7 @@ impl FnScopes {
     }
 }
 
+#[derive(Debug)]
 struct ScopeData {
     parent: Option<ScopeId>,
     entries: Vec<ScopeEntry>
@@ -149,3 +209,12 @@ impl ScopeEntry {
             .unwrap()
     }
 }
+
+impl fmt::Debug for ScopeEntry {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("ScopeEntry")
+         .field("name", &self.name())
+         .field("syntax", &self.syntax)
+         .finish()
+    }
+}
diff --git a/crates/libeditor/tests/test.rs b/crates/libeditor/tests/test.rs
index 7979bfffe..d051980b0 100644
--- a/crates/libeditor/tests/test.rs
+++ b/crates/libeditor/tests/test.rs
@@ -273,6 +273,19 @@ fn quux(x: i32) {
 }
 ", r#"[CompletionItem { name: "y" },
        CompletionItem { name: "x" }]"#);
+
+    do_check(r"
+fn quux() {
+    if let Some(x) = foo() {
+        let y = 92;
+    };
+    if let Some(a) = bar() {
+        let b = 62;
+        1 + <|>
+    }
+}
+", r#"[CompletionItem { name: "b" },
+       CompletionItem { name: "a" }]"#);
 }
 
 fn file(text: &str) -> File {