Improve parser/codegen support for paren expressions (fixes #291)

opal · Oct 7, 2013 · 888b783 · 888b783
1 parent 0078289
commit 888b783
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Showing 5 changed files with 46 additions and 11 deletions.
diff --git a/lib/opal/grammar.rb b/lib/opal/grammar.rb
diff --git a/lib/opal/grammar.y b/lib/opal/grammar.y
@@ -766,7 +766,7 @@ primary:
     }
   | PAREN_BEG compstmt ')'
     {
-      result = val[1] || s(:nil)
+      result = s(:paren, val[1] || s(:nil))
     }
   | primary_value '::' CONSTANT
     {

diff --git a/lib/opal/parser.rb b/lib/opal/parser.rb
@@ -915,7 +915,7 @@ def process_arglist(sexp, level)
 
     # s(:splat, sexp)
     def process_splat(sexp, level)
-      if sexp.first == [:nil]
+      if sexp.first == [:nil] or sexp.first == [:paren, [:nil]]
         [f("[]")]
       elsif sexp.first.first == :sym
         [f("["), process(sexp[0]), f("]")]
@@ -2248,6 +2248,27 @@ def process_begin(exp, level)
       end
     end
 
+    def process_paren(sexp, level)
+      if sexp[0][0] == :block
+        result = []
+
+        sexp[0][1..-1].each do |part|
+          result << f(', ') unless result.empty?
+          result << process(part, :expr)
+        end
+
+        [f('('), result, f(')')]
+      else
+        result = process sexp[0], level
+
+        unless level == :stmt
+          result = [f('('), result, f(')')]
+        end
+
+        result
+      end
+    end
+
     def process_next(exp, level)
       if in_while?
         f("continue;", exp)

diff --git a/spec/opal/language/paren_spec.rb b/spec/opal/language/paren_spec.rb
@@ -0,0 +1,14 @@
+require 'spec_helper'
+
+describe "Parens" do
+  it "can be used to group expressions" do
+    (self.class; self.to_s; 42).should == 42
+    (3.142).should == 3.142
+    ().should == nil
+  end
+
+  it "generates code that contains the expression in precedence" do
+    foo = 100
+    ((foo += 42) == 142).should == true
+  end
+end
diff --git a/spec/parser/call_spec.rb b/spec/parser/call_spec.rb
@@ -83,24 +83,24 @@
 describe "Operator precedence" do
   it "should be raised with parentheses" do
    opal_parse("(1 + 2) + (3 - 4)").should == [:call,
-                                               [:call, [:int, 1], :+, [:arglist, [:int, 2]]],
+                                               [:paren, [:call, [:int, 1], :+, [:arglist, [:int, 2]]]],
                                                :+,
-                                               [:arglist, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]],
+                                               [:arglist, [:paren, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]]],
                                               ]
    opal_parse("(1 + 2) - (3 - 4)").should == [:call,
-                                               [:call, [:int, 1], :+, [:arglist, [:int, 2]]],
+                                               [:paren, [:call, [:int, 1], :+, [:arglist, [:int, 2]]]],
                                                :-,
-                                               [:arglist, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]],
+                                               [:arglist, [:paren, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]]],
                                               ]
    opal_parse("(1 + 2) * (3 - 4)").should == [:call,
-                                               [:call, [:int, 1], :+, [:arglist, [:int, 2]]],
+                                               [:paren, [:call, [:int, 1], :+, [:arglist, [:int, 2]]]],
                                                :*,
-                                               [:arglist, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]],
+                                               [:arglist, [:paren, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]]],
                                               ]
    opal_parse("(1 + 2) / (3 - 4)").should == [:call,
-                                               [:call, [:int, 1], :+, [:arglist, [:int, 2]]],
+                                               [:paren, [:call, [:int, 1], :+, [:arglist, [:int, 2]]]],
                                                :/,
-                                               [:arglist, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]],
+                                               [:arglist, [:paren, [:call, [:int, 3], :-, [:arglist, [:int, 4]]]]],
                                               ]
   end
 end