Extend {foo} syntax to allow {"foo"} as well.

Useful when "foo" contains unusual characters. Should help with
the issues #7, #38, #40, #42.

execute.c

@@ -208,6 +208,17 @@ jv jq_next() {
       break;
     }
 
+    case DUP2: {
+      stackval keep = stack_pop();
+      stackval v = stack_pop();
+      stackval v2 = v;
+      v2.value = jv_copy(v.value);
+      stack_push(v);
+      stack_push(keep);
+      stack_push(v2);
+      break;
+    }
+
     case SWAP: {
       stackval a = stack_pop();
       stackval b = stack_pop();

opcode_list.h

@@ -1,5 +1,6 @@
 OP(LOADK, CONSTANT, 1, 1)
 OP(DUP,   NONE,     1, 2)
+OP(DUP2,  NONE,     2, 3)
 OP(SWAP,  NONE,     2, 2)
 OP(POP,   NONE,     1, 0)
 OP(LOADV, VARIABLE, 1, 1)

parser.y

@@ -414,6 +414,10 @@ MkDictPair
 | String ':' ExpD {
   $$ = gen_dictpair($1, $3);
   }
+| String {
+  $$ = gen_dictpair($1, BLOCK(gen_op_simple(POP), gen_op_simple(DUP2),
+                              gen_op_simple(DUP2), gen_op_simple(INDEX)));
+  }
 | IDENT {
   $$ = gen_dictpair(gen_const(jv_copy($1)),
                     gen_index(gen_noop(), gen_const($1)));

testdata

@@ -64,6 +64,10 @@ null
 {"a":1, "b":2, "c":3, "d":"c"}
 {"a":1, "b":2, "c":1, "e":2}
 
+{"a",b,"a$\(1+1)"}
+{"a":1, "b":2, "c":3, "a$2":4}
+{"a":1, "b":2, "a$2":4}
+
 #
 # Field access, piping
 #