Add some clarifications

src/style-spec/expression/parsing_context.js

@@ -86,28 +86,24 @@ class ParsingContext {
  const expected = context.expectedType;
  const actual = parsed.type;
 
- // When we expect a number, string, or boolean but have a
- // Value, wrap it in a refining assertion, and when we expect
- // a Color but have a String or Value, wrap it in "to-color"
- // coercion.
- const canAssert = expected.kind === 'string' ||
- expected.kind === 'number' ||
- expected.kind === 'boolean';
- const canAnnotate =
- (actual.kind === 'value' && (canAssert || expected.kind === 'array')) ||
- expected.kind === 'color' && (actual.kind === 'value' || actual.kind === 'string');
-
- if (canAnnotate && !options.omitTypeAnnotations) {
- if (canAssert) {
+ // When we expect a number, string, boolean, or array but
+ // have a Value, we can wrap it in a refining assertion.
+ // When we expect a Color but have a String or Value, we
+ // can wrap it in "to-color" coercion.
+ // Otherwise, we do static type-checking.
+ if ((expected.kind === 'string' || expected.kind === 'number' || expected.kind === 'boolean') && actual.kind === 'value') {
+ if (!options.omitTypeAnnotations) {
  parsed = new Assertion(expected, [parsed]);
- } else if (expected.kind === 'array') {
+ }
+ } else if (expected.kind === 'array' && actual.kind === 'value') {
+ if (!options.omitTypeAnnotations) {
  parsed = new ArrayAssertion(expected, parsed);
- } else if (expected.kind === 'color') {
+ }
+ } else if (expected.kind === 'color' && (actual.kind === 'value' || actual.kind === 'string')) {
+ if (!options.omitTypeAnnotations) {
  parsed = new Coercion(expected, [parsed]);
  }
- }
-
- if (!canAnnotate && context.checkSubtype(context.expectedType, parsed.type)) {
+ } else if (context.checkSubtype(context.expectedType, parsed.type)) {
  return null;
  }
  }