From 9679106c8ca17e057827c3aeeedc35430cc103d9 Mon Sep 17 00:00:00 2001
From: Kanit Wongsuphasawat <kanitw@gmail.com>
Date: Wed, 15 Feb 2017 22:15:49 -0800
Subject: [PATCH] [WIP] Make `field()` correctly escape `[]`

Fix #1949
---
 src/fielddef.ts | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/fielddef.ts b/src/fielddef.ts
index 818bf43199..3a58a2b837 100644
--- a/src/fielddef.ts
+++ b/src/fielddef.ts
@@ -137,6 +137,14 @@ export interface FieldRefOption {
 
 export function field(fieldDef: FieldDef, opt: FieldRefOption = {}) {
   let field = fieldDef.field;
+
+  const bracketsEscaped = field.charAt(0) === '['
+    && field.charAt(field.length - 1) === ']';
+
+  if (bracketsEscaped) {
+    field = field.slice(1, field.length -1);
+  }
+
   let prefix = opt.prefix;
   let suffix = opt.suffix;
 
@@ -170,10 +178,11 @@ export function field(fieldDef: FieldDef, opt: FieldRefOption = {}) {
   }
 
   if (opt.datum) {
-    field = `datum["${field}"]`;
+    // for datum, we never have to wrap with []
+    return `datum["${field}"]`;
   }
 
-  return field;
+  return bracketsEscaped ? `[${field}]` : field;
 }
 
 function _isFieldDimension(fieldDef: FieldDef) {