fix(transform): confused by comments, whitespace

- property names can't contain whitespace
- there can be whitespace before the colon
- comments can appear before property names
- property values can contain newlines
- !important must be at end of value

This doesn't cover everything, because, for example, there could be
comments mixed into the property value, and we don't look for them. But
it's probably not necessary either.

Along with the above, capture all the internal whitespace for fidelity
between input and output. We are replacing values, not reformatting the
CSS.

packages/core/src/transform.test.ts

@@ -0,0 +1,31 @@
+import { transform } from './transform'
+
+const props = { theme: { colors: { black: '#000' } } }
+
+const transformToStr = (s) =>
+  transform(s)
+    .map((x) => (typeof x === 'function' ? x(props) : x))
+    .join('')
+
+describe('#transform', () => {
+  it('replaces name/value pair with various whitespace', () => {
+    expect(transformToStr('color:black;')).toBe('color:#000;')
+    expect(transformToStr(' color : black ; ')).toBe(' color : #000 ; ')
+  })
+
+  it('replaces name/value pair within rule', () => {
+    expect(transformToStr('.my-class { color: black; }')).toBe(
+      '.my-class { color: #000; }',
+    )
+  })
+
+  it('handles !important', () => {
+    expect(transformToStr('color: black !important;')).toBe(
+      'color: #000 !important;',
+    )
+  })
+
+  it("isn't confused by comments", () => {
+    expect(transformToStr('/* hi */color:black;')).toBe('/* hi */color:#000;')
+  })
+})

packages/core/src/transform.ts

@@ -1,19 +1,21 @@
 /* eslint-disable no-continue, no-loop-func, no-cond-assign */
 import { propGetters } from './propGetters'
 
-// prettier-ignore
-const PROP_REGEXP = new RegExp(
-  `(\\s*)` +            // leading whitespace
-  `([^&{}:;\\n]+)` +    // property name
-  `:\\s*` +             // colon, whitespace
-  `([^&{}:;\\n]+)` +    // property value
-  `(\\s*);`,            // trailing whitespace, semicolon
-  `g`,                  // flags
-)
+// prop name is an ident: word chars, underscore and dash.
+const PROP_CHAR = `[-\\w]`
+
+// prop value consists of non-semis unless backslash-escaped.
+const VALUE_CHAR = `(?:\\\\.|[^\\\\;])`
 
 // prettier-ignore
-const IMPORTANT_REGEXP = new RegExp(
-  `\\s*!important\\s*`, // important flag, surrounding whitespace
+const PROP_REGEXP = new RegExp(
+  `(${PROP_CHAR}+)` +   // capture prop name
+  `(\\s*:\\s*)` +       // colon & whitespace
+  `(?=\\S)` +           // prop value starts with non-whitespace
+  `(${VALUE_CHAR}*?)` + // capture prop value (non-greedy)
+  `(\\s*!important)?` + // capture !important
+  `(\\s*;)`,            // semi & whitespace
+  `gs`,                 // flags
 )
 
 export function transform(rawValue: any) {
@@ -22,17 +24,12 @@ export function transform(rawValue: any) {
   let lastIndex = 0
   const values = []
   while ((matches = PROP_REGEXP.exec(rawValue))) {
-    const [, start, prop, propValue, end] = matches
+    const [, prop, colon, value, imp, semi] = matches
     const getter = (propGetters as any)[prop]
     if (getter) {
-      const hasImportant = IMPORTANT_REGEXP.test(propValue)
-      const cleanValue = propValue.replace(IMPORTANT_REGEXP, '')
       values.push(rawValue.slice(lastIndex, matches.index))
       values.push(
-        (p: object) =>
-          `${start}${prop}: ${getter(cleanValue)(p)}${
-            hasImportant ? ' !important' : ''
-          };${end}`,
+        (p: object) => `${prop}${colon}${getter(value)(p)}${imp || ''}${semi}`,
       )
       lastIndex = matches.index + matches[0].length
     }