syntax: add support for quoting arms

Author: erickt

src/libsyntax/ext/base.rs

@@ -382,6 +382,9 @@ fn initial_syntax_expander_table() -> SyntaxEnv {
     syntax_expanders.insert(intern("quote_pat"),
                        builtin_normal_expander(
                             ext::quote::expand_quote_pat));
+    syntax_expanders.insert(intern("quote_arm"),
+                       builtin_normal_expander(
+                            ext::quote::expand_quote_arm));
     syntax_expanders.insert(intern("quote_stmt"),
                        builtin_normal_expander(
                             ext::quote::expand_quote_stmt));

src/libsyntax/ext/quote.rs

@@ -349,6 +349,14 @@ pub fn expand_quote_pat(cx: &mut ExtCtxt,
     base::MacExpr::new(expanded)
 }
 
+pub fn expand_quote_arm(cx: &mut ExtCtxt,
+                        sp: Span,
+                        tts: &[ast::TokenTree])
+                        -> Box<base::MacResult> {
+    let expanded = expand_parse_call(cx, sp, "parse_arm", vec!(), tts);
+    base::MacExpr::new(expanded)
+}
+
 pub fn expand_quote_ty(cx: &mut ExtCtxt,
                        sp: Span,
                        tts: &[ast::TokenTree])

src/libsyntax/parse/parser.rs

@@ -2727,37 +2727,41 @@ impl<'a> Parser<'a> {
         self.commit_expr_expecting(discriminant, token::LBRACE);
         let mut arms: Vec<Arm> = Vec::new();
         while self.token != token::RBRACE {
-            let attrs = self.parse_outer_attributes();
-            let pats = self.parse_pats();
-            let mut guard = None;
-            if self.eat_keyword(keywords::If) {
-                guard = Some(self.parse_expr());
-            }
-            self.expect(&token::FAT_ARROW);
-            let expr = self.parse_expr_res(RESTRICT_STMT_EXPR);
-
-            let require_comma =
-                !classify::expr_is_simple_block(expr)
-                && self.token != token::RBRACE;
-
-            if require_comma {
-                self.commit_expr(expr, &[token::COMMA], &[token::RBRACE]);
-            } else {
-                self.eat(&token::COMMA);
-            }
-
-            arms.push(ast::Arm {
-                attrs: attrs,
-                pats: pats,
-                guard: guard,
-                body: expr
-            });
+            arms.push(self.parse_arm());
         }
         let hi = self.span.hi;
         self.bump();
         return self.mk_expr(lo, hi, ExprMatch(discriminant, arms));
     }
 
+    pub fn parse_arm(&mut self) -> Arm {
+        let attrs = self.parse_outer_attributes();
+        let pats = self.parse_pats();
+        let mut guard = None;
+        if self.eat_keyword(keywords::If) {
+            guard = Some(self.parse_expr());
+        }
+        self.expect(&token::FAT_ARROW);
+        let expr = self.parse_expr_res(RESTRICT_STMT_EXPR);
+
+        let require_comma =
+            !classify::expr_is_simple_block(expr)
+            && self.token != token::RBRACE;
+
+        if require_comma {
+            self.commit_expr(expr, &[token::COMMA], &[token::RBRACE]);
+        } else {
+            self.eat(&token::COMMA);
+        }
+
+        ast::Arm {
+            attrs: attrs,
+            pats: pats,
+            guard: guard,
+            body: expr,
+        }
+    }
+
     /// Parse an expression
     pub fn parse_expr(&mut self) -> Gc<Expr> {
         return self.parse_expr_res(UNRESTRICTED);

src/test/run-make/graphviz-flowgraph/f07.dot-expected.dot

@@ -6,7 +6,7 @@ digraph block {
     N4[label="expr 777i"];
     N5[label="expr 7777i"];
     N6[label="expr [7i, 77i, 777i, 7777i]"];
-    N7[label="expr match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y }"];
+    N7[label="expr match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y, }"];
     N8[label="(dummy_node)"];
     N9[label="local x"];
     N10[label="local y"];
@@ -15,7 +15,7 @@ digraph block {
     N13[label="expr x"];
     N14[label="expr y"];
     N15[label="expr x + y"];
-    N16[label="block { match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y }; }"];
+    N16[label="block { match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y, }; }"];
     N0 -> N2;
     N2 -> N3;
     N3 -> N4;

src/test/run-make/graphviz-flowgraph/f13.dot-expected.dot

@@ -7,7 +7,7 @@ digraph block {
     N5[label="local x"];
     N6[label="local _y"];
     N7[label="expr x"];
-    N8[label="expr match x { E13a => _y = 1, E13b(v) => _y = v + 1 }"];
+    N8[label="expr match x { E13a => _y = 1, E13b(v) => _y = v + 1, }"];
     N9[label="(dummy_node)"];
     N10[label="local E13a"];
     N11[label="expr 1"];
@@ -21,7 +21,7 @@ digraph block {
     N19[label="expr v + 1"];
     N20[label="expr _y"];
     N21[label="expr _y = v + 1"];
-    N22[label="block {\l    let x = E13b(13);\l    let _y;\l    match x { E13a => _y = 1, E13b(v) => _y = v + 1 }\l}\l"];
+    N22[label="block {\l    let x = E13b(13);\l    let _y;\l    match x { E13a => _y = 1, E13b(v) => _y = v + 1, }\l}\l"];
     N0 -> N2;
     N2 -> N3;
     N3 -> N4;

src/test/run-pass-fulldeps/qquote.rs

@@ -72,6 +72,8 @@ fn main() {
     let pat = quote_pat!(cx, Some(_));
     check_pp(ext_cx, pat, pprust::print_pat, "Some(_)".to_string());
 
+    let arm = quote_arm!(cx, (ref x, ref y) => (x, y));
+    check_pp(ext_cx, arm, pprust::print_stmt, "(ref x, ref y) = (x, y)".to_string());
 }
 
 fn check_pp<T>(cx: fake_ext_ctxt,

src/test/run-pass-fulldeps/quote-tokens.rs

@@ -26,6 +26,7 @@ fn syntax_extension(cx: &ExtCtxt) {
     let _b: Option<Gc<syntax::ast::Item>> = quote_item!(cx, static foo : int = $e_toks; );
     let _c: Gc<syntax::ast::Pat> = quote_pat!(cx, (x, 1 .. 4, *) );
     let _d: Gc<syntax::ast::Stmt> = quote_stmt!(cx, let x = $a; );
+    let _d: syntax::ast::Arm = quote_arm!(cx, (ref x, ref y) = (x, y) );
     let _e: Gc<syntax::ast::Expr> = quote_expr!(cx, match foo { $p_toks => 10 } );
 
     let _f: Gc<syntax::ast::Expr> = quote_expr!(cx, ());