Field punning shorthand syntax for records, closes #16

edubart · Sep 25, 2020 · 4539446 · 4539446
1 parent 29bc9b2
commit 4539446
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Showing 3 changed files with 13 additions and 3 deletions.
diff --git a/nelua/syntaxdefs.lua b/nelua/syntaxdefs.lua
@@ -10,6 +10,7 @@ local function get_parser()
 
   local parser = PEGParser()
   parser:set_astbuilder(astbuilder)
+  local to_astnode = parser.defs.to_astnode
 
   -- spaces including new lines
   parser:set_peg("SPACE", "%s")
@@ -419,7 +420,9 @@ local function get_parser()
         {| (table_row (%SEPARATOR table_row)* %SEPARATOR?)? |}
       eRCURLY) -> to_astnode
     table_row <- table_pair / expr
-    table_pair <- ({} '' -> 'Pair' (%LBRACKET eexpr eRBRACKET / name) %ASSIGN eexpr) -> to_astnode
+    table_pair <-
+      ({} '' -> 'Pair' (%LBRACKET eexpr eRBRACKET / name) %ASSIGN eexpr) -> to_astnode /
+      ({} %ASSIGN -> 'Pair' name) -> to_punned_pair_astnode
 
     doexpr <-
       ({} %LPAREN %DO -> 'DoExpr' block eEND eRPAREN) -> to_astnode
@@ -555,7 +558,11 @@ local function get_parser()
 
     name    <- %cNAME / ppname
     id      <- ({} '' -> 'Id' name) -> to_astnode
-  ]])
+  ]], {
+    to_punned_pair_astnode = function(pos, tag, name)
+      return to_astnode(pos, tag, name, to_astnode(pos+1, 'Id', name))
+    end
+  })
 
   -- operators
   grammar:set_pegs([[

diff --git a/spec/02-syntaxdefs_spec.lua b/spec/02-syntaxdefs_spec.lua
@@ -446,14 +446,15 @@ describe("expression", function()
     }}}})
   end)
   it("table", function()
-    assert.parse_ast(nelua_parser, "return {}, {a}, {a,b}, {a=b}, {[a] = b}",
+    assert.parse_ast(nelua_parser, "return {}, {a}, {a,b}, {a=b}, {[a] = b}, {=a}",
       n.Block{{
         n.Return{{
           n.Table{{}},
           n.Table{{ n.Id{'a'} }},
           n.Table{{ n.Id{'a'}, n.Id{'b'} }},
           n.Table{{ n.Pair{'a', n.Id{'b'}} }},
           n.Table{{ n.Pair{n.Id{'a'}, n.Id{'b'}} }},
+          n.Table{{ n.Pair{'a', n.Id{'a'}} }},
     }}}})
   end)
   it("surrounded expression", function()

diff --git a/spec/05-cgenerator_spec.lua b/spec/05-cgenerator_spec.lua
@@ -1664,6 +1664,8 @@ it("records", function()
     assert(Point({1,2}).y == 2)
     assert(Point({x=1,2}).y == 2)
     assert(Point({1,y=2}).x == 1)
+    local x, y = 1, 2
+    assert(Point({=x,=y}).y == 2)
   ]])
   assert.run_c([[
     local Point = @record {x: integer, y: integer}