bail out of change tracking on encountering function calls in templates. TODO avoid bailing where possible

src/compile/Component.ts

@@ -360,6 +360,11 @@ export default class Component {
 		});
 	}
 
+	findDependenciesForFunctionCall(name) {
+		// TODO
+		return null;
+	}
+
 	walkJs() {
 		const { js } = this.ast;
 		if (!js) return;

src/compile/nodes/shared/Expression.ts

@@ -4,6 +4,7 @@ import isReference from 'is-reference';
 import flattenReference from '../../../utils/flattenReference';
 import { createScopes } from '../../../utils/annotateWithScopes';
 import { Node } from '../../../interfaces';
+import addToSet from '../../../utils/addToSet';
 
 const binaryOperators: Record<string, number> = {
 	'**': 15,
@@ -106,6 +107,19 @@ export default class Expression {
 					expression.thisReferences.push(node);
 				}
 
+				if (node.type === 'CallExpression') {
+					if (node.callee.type === 'Identifier') {
+						const dependencies_for_invocation = component.findDependenciesForFunctionCall(node.callee.name);
+						if (dependencies_for_invocation) {
+							addToSet(dependencies, dependencies_for_invocation);
+						} else {
+							dependencies.add('$$BAIL$$');
+						}
+					} else {
+						dependencies.add('$$BAIL$$');
+					}
+				}
+
 				if (isReference(node, parent)) {
 					const { name, nodes } = flattenReference(node);
 

src/compile/render-dom/wrappers/EachBlock.ts

@@ -427,6 +427,8 @@ export default class EachBlockWrapper extends Wrapper {
 		}
 
 		// TODO do this for keyed blocks as well
+		const bail = allDependencies.has('$$BAIL$$');
+
 		const condition = Array.from(allDependencies)
 			.map(dependency => `changed.${dependency}`)
 			.join(' || ');
@@ -476,7 +478,7 @@ export default class EachBlockWrapper extends Wrapper {
 				`;
 			}
 
-			block.builders.update.addBlock(deindent`
+			const update = deindent`
 				if (${condition}) {
 					${this.vars.each_block_value} = ${snippet};
 
@@ -488,8 +490,18 @@ export default class EachBlockWrapper extends Wrapper {
 
 					${destroy}
 				}
+			`;
+
+			if (bail) {
+				block.builders.update.addBlock(update);
+			} else {
+				block.builders.update.addBlock(deindent`
+					if (${condition}) {
+						${update}
+					}
 				`);
 			}
+		}
 
 		if (outroBlock && this.renderer.component.options.nestedTransitions) {
 			const countdown = block.getUniqueName('countdown');

src/compile/render-dom/wrappers/Element/Attribute.ts

@@ -99,7 +99,7 @@ export default class AttributeWrapper {
 			const isSelectValueAttribute =
 				name === 'value' && element.node.name === 'select';
 
-			const shouldCache = this.node.shouldCache || isSelectValueAttribute;
+			const shouldCache = !this.node.dependencies.has('$$BAIL$$') && (this.node.shouldCache || isSelectValueAttribute);
 
 			const last = shouldCache && block.getUniqueName(
 				`${element.var}_${name.replace(/[^a-zA-Z_$]/g, '_')}_value`

src/compile/render-dom/wrappers/Element/StyleAttribute.ts

@@ -44,6 +44,11 @@ export default class StyleAttributeWrapper extends AttributeWrapper {
 						.join(' + ');
 
 				if (propDependencies.size) {
+					if (propDependencies.has('$$BAIL$$')) {
+						block.builders.update.addLine(
+							`@setStyle(${this.parent.var}, "${prop.key}", ${value});`
+						);
+					} else {
 						const dependencies = Array.from(propDependencies);
 						const condition = (
 							(block.hasOutros ? `!#current || ` : '') +
@@ -55,6 +60,7 @@ export default class StyleAttributeWrapper extends AttributeWrapper {
 							`@setStyle(${this.parent.var}, "${prop.key}", ${value});`
 						);
 					}
+				}
 			} else {
 				value = stringify(prop.value[0].data);
 			}

src/compile/render-dom/wrappers/Element/index.ts

@@ -588,7 +588,7 @@ export default class ElementWrapper extends Wrapper {
 		this.node.attributes
 			.filter(attr => attr.type === 'Attribute' || attr.type === 'Spread')
 			.forEach(attr => {
-				const condition = attr.dependencies.size > 0
+				const condition = (attr.dependencies.size > 0 && !attr.dependencies.has('$$BAIL$$'))
 					? `(${[...attr.dependencies].map(d => `changed.${d}`).join(' || ')})`
 					: null;
 

src/compile/render-dom/wrappers/InlineComponent/index.ts

@@ -134,6 +134,8 @@ export default class InlineComponentWrapper extends Wrapper {
 				this.node.attributes.forEach(attr => {
 					const { name, dependencies } = attr;
 
+					// TODO probably need to account for $$BAIL$$ but
+					// not totally sure how. will come back to it
 					const condition = dependencies.size > 0 && (dependencies.size !== allDependencies.size)
 						? `(${[...dependencies].map(d => `changed.${d}`).join(' || ')})`
 						: null;

src/compile/render-dom/wrappers/shared/Tag.ts

@@ -48,9 +48,13 @@ export default class Tag extends Wrapper {
 
 			const updateCachedValue = `${value} !== (${value} = ${snippet})`;
 
-			const condition = this.node.shouldCache ?
-				(dependencies.size ? `(${changedCheck}) && ${updateCachedValue}` : updateCachedValue) :
-				changedCheck;
+			const condition = dependencies.has('$$BAIL$$')
+				? updateCachedValue
+				: this.node.shouldCache
+					? dependencies.size > 0
+						? `(${changedCheck}) && ${updateCachedValue}`
+						: updateCachedValue
+					: changedCheck;
 
 			block.builders.update.addConditional(
 				condition,

src/utils/CodeBuilder.ts

@@ -35,7 +35,8 @@ export default class CodeBuilder {
 	addConditional(condition: string, body: string) {
 		this.reifyConditions();
 
-		body = body.replace(/^/gm, `${this.indent}\t`);
+		const indent = this.indent + (condition ? '\t' : '');
+		body = body.replace(/^/gm, indent);
 
 		if (condition === this.lastCondition) {
 			this.result += `\n${body}`;
@@ -44,7 +45,11 @@ export default class CodeBuilder {
 				this.result += `\n${this.indent}}`;
 			}
 
-			this.result += `${this.last === ChunkType.Block ? '\n\n' : '\n'}${this.indent}if (${condition}) {\n${body}`;
+			const block = condition
+				? `if (${condition}) {\n${body}`
+				: body;
+
+			this.result += `${this.last === ChunkType.Block ? '\n\n' : '\n'}${this.indent}${block}`;
 			this.lastCondition = condition;
 		}
 

test/runtime/samples/computed-values/_config.js

@@ -1,10 +1,16 @@
 export default {
-	html: '<p>1 + 2 = 3</p>\n<p>3 * 3 = 9</p>',
+	html: `
+		<p>1 + 2 = 3</p>
+		<p>3 * 3 = 9</p>
+	`,
 
 	test(assert, component, target) {
 		component.a = 3;
-		assert.equal(component.c, 5);
-		assert.equal(component.cSquared, 25);
-		assert.equal(target.innerHTML, '<p>3 + 2 = 5</p>\n<p>5 * 5 = 25</p>');
+		assert.equal(component.c(), 5);
+		assert.equal(component.cSquared(), 25);
+		assert.htmlEqual(target.innerHTML, `
+			<p>3 + 2 = 5</p>
+			<p>5 * 5 = 25</p>
+		`);
 	}
 };

test/runtime/samples/computed-values/main.html

@@ -2,13 +2,11 @@
 	export let a = 1;
 	export let b = 2;
 
-	function c() {
+	export function c() {
 		return a + b;
 	}
 
-	function cSquared() {
-		return c() * c();
-	}
+	export const cSquared = () => c() * c();
 </script>
 
 <p>{a} + {b} = {c()}</p>