fix: dynamic styles are mapped to bindings when generating builder

.changeset/large-yaks-matter.md

@@ -0,0 +1,5 @@
+---
+'@builder.io/mitosis': patch
+---
+
+Builder: dynamic styles are mapped to bindings when generating

packages/core/src/__tests__/builder.test.ts

@@ -764,6 +764,35 @@ describe('Builder', () => {
       }
       "
     `);
+
+    const json = componentToBuilder()({ component: mitosis });
+    expect(json).toMatchInlineSnapshot(`
+      {
+        "data": {
+          "blocks": [
+            {
+              "@type": "@builder.io/sdk:Element",
+              "actions": {},
+              "bindings": {
+                "responsiveStyles.large.color": "state.color",
+                "responsiveStyles.small.left": "state.left",
+                "responsiveStyles.small.top": "state.top",
+                "style.fontSize": "state.fontSize",
+              },
+              "children": [],
+              "code": {
+                "actions": {},
+                "bindings": {},
+              },
+              "properties": {},
+              "tagName": "div",
+            },
+          ],
+          "jsCode": "",
+          "tsCode": "",
+        },
+      }
+    `);
   });
 });
 

packages/core/src/generators/builder/generator.ts

@@ -14,11 +14,13 @@ import { replaceNodes } from '@/helpers/replace-identifiers';
 import { checkHasState } from '@/helpers/state';
 import { isBuilderElement, symbolBlocksAsChildren } from '@/parsers/builder';
 import { hashCodeAsString } from '@/symbols/symbol-processor';
-import { ForNode, MitosisNode } from '@/types/mitosis-node';
+import { Binding, ForNode, MitosisNode } from '@/types/mitosis-node';
 import { MitosisStyles } from '@/types/mitosis-styles';
 import { TranspilerArgs } from '@/types/transpiler';
 import { traverse as babelTraverse, types } from '@babel/core';
 import generate from '@babel/generator';
+import { parseExpression } from '@babel/parser';
+import type { Node } from '@babel/types';
 import { BuilderContent, BuilderElement } from '@builder.io/sdk';
 import json5 from 'json5';
 import { attempt, mapValues, omit, omitBy, set } from 'lodash';
@@ -333,6 +335,150 @@ const processLocalizedValues = (element: BuilderElement, node: MitosisNode) => {
   return element;
 };
 
+/**
+ * Turns a stringified object into an object that can be looped over.
+ * Since values in the stringified object could be JS expressions, all
+ * values in the resulting object will remain strings.
+ * @param input - The stringified object
+ */
+const parseJSObject = (
+  input: string,
+): {
+  parsed: Record<string, string>;
+  unparsed?: string;
+} => {
+  const unparsed: string[] = [];
+  let parsed: Record<string, string> = {};
+
+  try {
+    const ast = parseExpression(`(${input})`, {
+      plugins: ['jsx', 'typescript'],
+      sourceType: 'module',
+    });
+
+    if (ast.type !== 'ObjectExpression') {
+      return { parsed, unparsed: input };
+    }
+
+    for (const prop of ast.properties) {
+      /**
+       * If the object includes spread or method, we stop. We can't really break the component into Key/Value
+       * and the whole expression is considered dynamic. We return `false` to signify that.
+       */
+      if (prop.type === 'ObjectMethod' || prop.type === 'SpreadElement') {
+        if (!!prop.start && !!prop.end) {
+          if (typeof input === 'string') {
+            unparsed.push(input.slice(prop.start - 1, prop.end - 1));
+          }
+        }
+        continue;
+      }
+
+      /**
+       * Ignore shorthand objects when processing incomplete objects. Otherwise we may
+       * create identifiers unintentionally.
+       * Example: When accounting for shorthand objects, "{ color" would become
+       * { color: color } thus creating a "color" identifier that does not exist.
+       */
+      if (prop.type === 'ObjectProperty') {
+        if (prop.extra?.shorthand) {
+          if (typeof input === 'string') {
+            unparsed.push(input.slice(prop.start! - 1, prop.end! - 1));
+          }
+          continue;
+        }
+
+        let key = '';
+        if (prop.key.type === 'Identifier') {
+          key = prop.key.name;
+        } else if (prop.key.type === 'StringLiteral') {
+          key = prop.key.value;
+        } else {
+          continue;
+        }
+
+        if (typeof input === 'string') {
+          const [val, err] = extractValue(input, prop.value);
+          if (err === null) {
+            parsed[key] = val;
+          }
+        }
+      }
+    }
+
+    return {
+      parsed,
+      unparsed: unparsed.length > 0 ? `{${unparsed.join('\n')}}` : undefined,
+    };
+  } catch (err) {
+    return {
+      parsed,
+      unparsed: unparsed.length > 0 ? `{${unparsed.join('\n')}}` : undefined,
+    };
+  }
+};
+
+const extractValue = (input: string, node: Node | null): [string, null] | [null, string] => {
+  const start = node?.loc?.start;
+  const end = node?.loc?.end;
+  const startIndex =
+    start !== undefined && 'index' in start && typeof start['index'] === 'number'
+      ? start['index']
+      : undefined;
+  const endIndex =
+    end !== undefined && 'index' in end && typeof end['index'] === 'number'
+      ? end['index']
+      : undefined;
+
+  if (startIndex === undefined || endIndex === undefined || node === null) {
+    const err = `bad value: ${node}`;
+    return [null, err];
+  }
+
+  const value = input.slice(startIndex - 1, endIndex - 1);
+  return [value, null];
+};
+
+/**
+ * Maps and styles that are bound with dynamic values onto their respective
+ * binding keys for Builder elements. This function also maps media queries
+ * with dynamic values.
+ * @param - bindings - The bindings object that has your styles. This param
+ * will be modified in-place, and the old "style" key will be removed.
+ */
+const mapBoundStyles = (bindings: { [key: string]: Binding | undefined }) => {
+  const styles = bindings['style'];
+  if (!styles) {
+    return;
+  }
+  const { parsed } = parseJSObject(styles.code);
+
+  for (const key in parsed) {
+    const mediaQueryMatch = key.match(mediaQueryRegex);
+
+    if (mediaQueryMatch) {
+      const { parsed: mParsed } = parseJSObject(parsed[key]);
+      const [_, pixelSize] = mediaQueryMatch;
+      const size = sizes.getSizeForWidth(Number(pixelSize));
+      for (const mKey in mParsed) {
+        bindings[`responsiveStyles.${size}.${mKey}`] = {
+          code: mParsed[mKey],
+          bindingType: 'expression',
+          type: 'single',
+        };
+      }
+    } else {
+      bindings[`style.${key}`] = {
+        code: parsed[key],
+        bindingType: 'expression',
+        type: 'single',
+      };
+    }
+  }
+
+  delete bindings['style'];
+};
+
 export const blockToBuilder = (
   json: MitosisNode,
   options: ToBuilderOptions = {},
@@ -393,6 +539,10 @@ export const blockToBuilder = (
         actionBody;
       delete bindings[key];
     }
+
+    if (key === 'style') {
+      mapBoundStyles(bindings);
+    }
   }
 
   const builderBindings: Record<string, string> = {};