handle invalid expressions

packages/svelte/src/compiler/phases/1-parse/read/expression.js

@@ -39,6 +39,38 @@ export default function read_expression(parser) {
 
 		return /** @type {Expression} */ (node);
 	} catch (err) {
+		if (parser.loose) {
+			// Find the next } and treat it as the end of the expression
+			let index = parser.index;
+			let num_braces = 0;
+			while (index < parser.template.length) {
+				const char = parser.template[index];
+				if (char === '{') num_braces += 1;
+				if (char === '}') {
+					if (num_braces === 0) {
+						// We assume that there's some kind of whitespace or the start of the closing tag after the closing brace,
+						// else this hints at a wrong counting of braces (e.g. in the case of foo={'hi}'})
+						if (!/[\s>/]/.test(parser.template[index + 1])) {
+							num_braces += 1;
+							continue;
+						}
+
+						const start = parser.index;
+						parser.index = index;
+						// We don't know what the expression is and signal this by returning an empty identifier
+						return {
+							type: 'Identifier',
+							start,
+							end: index,
+							name: ''
+						};
+					}
+					num_braces -= 1;
+				}
+				index += 1;
+			}
+		}
+
 		parser.acorn_error(err);
 	}
 }

packages/svelte/src/compiler/phases/1-parse/state/element.js

@@ -481,7 +481,7 @@ function read_attribute(parser) {
 			return spread;
 		} else {
 			const value_start = parser.index;
-			const name = parser.read_identifier();
+			let name = parser.read_identifier();
 
 			if (name === null) {
 				if (
@@ -491,9 +491,13 @@ function read_attribute(parser) {
 					// We're likely in an unclosed opening tag and did read part of a block.
 					// Return null to not crash the parser so it can continue with closing the tag.
 					return null;
-				}
+				} else if (parser.loose && parser.match('}')) {
+					// Likely in the middle of typing, just created the shorthand
+					name = '';
+				} else {
 					e.attribute_empty_shorthand(start);
 				}
+			}
 
 			parser.allow_whitespace();
 			parser.eat('}', true);

packages/svelte/tests/parser-legacy/samples/loose-invalid-expression/input.svelte

@@ -0,0 +1,8 @@
+<div {}></div>
+<div foo={}></div>
+
+<div foo={a.}></div>
+<div foo={'hi}'.}></div>
+<Component onclick={() => x.} />
+
+<input bind:value={a.} />

packages/svelte/tests/parser-legacy/samples/loose-invalid-expression/output.json

@@ -0,0 +1,206 @@
+{
+	"html": {
+		"type": "Fragment",
+		"start": 0,
+		"end": 140,
+		"children": [
+			{
+				"type": "Element",
+				"start": 0,
+				"end": 14,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 5,
+						"end": 7,
+						"name": "",
+						"value": [
+							{
+								"type": "AttributeShorthand",
+								"start": 6,
+								"end": 6,
+								"expression": {
+									"start": 6,
+									"end": 6,
+									"type": "Identifier",
+									"name": ""
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			},
+			{
+				"type": "Text",
+				"start": 14,
+				"end": 15,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "Element",
+				"start": 15,
+				"end": 33,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 20,
+						"end": 26,
+						"name": "foo",
+						"value": [
+							{
+								"type": "MustacheTag",
+								"start": 24,
+								"end": 26,
+								"expression": {
+									"type": "Identifier",
+									"start": 25,
+									"end": 25,
+									"name": ""
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			},
+			{
+				"type": "Text",
+				"start": 33,
+				"end": 35,
+				"raw": "\n\n",
+				"data": "\n\n"
+			},
+			{
+				"type": "Element",
+				"start": 35,
+				"end": 55,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 40,
+						"end": 48,
+						"name": "foo",
+						"value": [
+							{
+								"type": "MustacheTag",
+								"start": 44,
+								"end": 48,
+								"expression": {
+									"type": "Identifier",
+									"start": 45,
+									"end": 47,
+									"name": ""
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			},
+			{
+				"type": "Text",
+				"start": 55,
+				"end": 56,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "Element",
+				"start": 56,
+				"end": 80,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 61,
+						"end": 73,
+						"name": "foo",
+						"value": [
+							{
+								"type": "MustacheTag",
+								"start": 65,
+								"end": 73,
+								"expression": {
+									"type": "Identifier",
+									"start": 66,
+									"end": 72,
+									"name": ""
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			},
+			{
+				"type": "Text",
+				"start": 80,
+				"end": 81,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "InlineComponent",
+				"start": 81,
+				"end": 113,
+				"name": "Component",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 92,
+						"end": 110,
+						"name": "onclick",
+						"value": [
+							{
+								"type": "MustacheTag",
+								"start": 100,
+								"end": 110,
+								"expression": {
+									"type": "Identifier",
+									"start": 101,
+									"end": 109,
+									"name": ""
+								}
+							}
+						]
+					}
+				],
+				"children": []
+			},
+			{
+				"type": "Text",
+				"start": 113,
+				"end": 115,
+				"raw": "\n\n",
+				"data": "\n\n"
+			},
+			{
+				"type": "Element",
+				"start": 115,
+				"end": 140,
+				"name": "input",
+				"attributes": [
+					{
+						"start": 122,
+						"end": 137,
+						"type": "Binding",
+						"name": "value",
+						"expression": {
+							"type": "Identifier",
+							"start": 134,
+							"end": 136,
+							"name": ""
+						},
+						"modifiers": []
+					}
+				],
+				"children": []
+			}
+		]
+	}
+}

packages/svelte/tests/parser-modern/samples/loose-invalid-expression/input.svelte

@@ -0,0 +1,8 @@
+<div {}></div>
+<div foo={}></div>
+
+<div foo={a.}></div>
+<div foo={'hi}'.}></div>
+<Component onclick={() => x.} />
+
+<input bind:value={a.} />

packages/svelte/tests/parser-modern/samples/loose-invalid-expression/output.json

@@ -0,0 +1,218 @@
+{
+	"css": null,
+	"js": [],
+	"start": 0,
+	"end": 140,
+	"type": "Root",
+	"fragment": {
+		"type": "Fragment",
+		"nodes": [
+			{
+				"type": "RegularElement",
+				"start": 0,
+				"end": 14,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 5,
+						"end": 7,
+						"name": "",
+						"value": {
+							"type": "ExpressionTag",
+							"start": 6,
+							"end": 6,
+							"expression": {
+								"start": 6,
+								"end": 6,
+								"type": "Identifier",
+								"name": ""
+							}
+						}
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			},
+			{
+				"type": "Text",
+				"start": 14,
+				"end": 15,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "RegularElement",
+				"start": 15,
+				"end": 33,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 20,
+						"end": 26,
+						"name": "foo",
+						"value": {
+							"type": "ExpressionTag",
+							"start": 24,
+							"end": 26,
+							"expression": {
+								"type": "Identifier",
+								"start": 25,
+								"end": 25,
+								"name": ""
+							}
+						}
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			},
+			{
+				"type": "Text",
+				"start": 33,
+				"end": 35,
+				"raw": "\n\n",
+				"data": "\n\n"
+			},
+			{
+				"type": "RegularElement",
+				"start": 35,
+				"end": 55,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 40,
+						"end": 48,
+						"name": "foo",
+						"value": {
+							"type": "ExpressionTag",
+							"start": 44,
+							"end": 48,
+							"expression": {
+								"type": "Identifier",
+								"start": 45,
+								"end": 47,
+								"name": ""
+							}
+						}
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			},
+			{
+				"type": "Text",
+				"start": 55,
+				"end": 56,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "RegularElement",
+				"start": 56,
+				"end": 80,
+				"name": "div",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 61,
+						"end": 73,
+						"name": "foo",
+						"value": {
+							"type": "ExpressionTag",
+							"start": 65,
+							"end": 73,
+							"expression": {
+								"type": "Identifier",
+								"start": 66,
+								"end": 72,
+								"name": ""
+							}
+						}
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			},
+			{
+				"type": "Text",
+				"start": 80,
+				"end": 81,
+				"raw": "\n",
+				"data": "\n"
+			},
+			{
+				"type": "Component",
+				"start": 81,
+				"end": 113,
+				"name": "Component",
+				"attributes": [
+					{
+						"type": "Attribute",
+						"start": 92,
+						"end": 110,
+						"name": "onclick",
+						"value": {
+							"type": "ExpressionTag",
+							"start": 100,
+							"end": 110,
+							"expression": {
+								"type": "Identifier",
+								"start": 101,
+								"end": 109,
+								"name": ""
+							}
+						}
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			},
+			{
+				"type": "Text",
+				"start": 113,
+				"end": 115,
+				"raw": "\n\n",
+				"data": "\n\n"
+			},
+			{
+				"type": "RegularElement",
+				"start": 115,
+				"end": 140,
+				"name": "input",
+				"attributes": [
+					{
+						"start": 122,
+						"end": 137,
+						"type": "BindDirective",
+						"name": "value",
+						"expression": {
+							"type": "Identifier",
+							"start": 134,
+							"end": 136,
+							"name": ""
+						},
+						"modifiers": []
+					}
+				],
+				"fragment": {
+					"type": "Fragment",
+					"nodes": []
+				}
+			}
+		]
+	},
+	"options": null
+}