From ae3a00259a547bf56c6b4413f73af300cfbaf5ed Mon Sep 17 00:00:00 2001
From: pngwn <hello@pngwn.io>
Date: Thu, 3 Sep 2020 23:39:08 +0100
Subject: [PATCH] start moving errors into a single location

---
 package-lock.json                    |   6 +-
 package.json                         |   2 +-
 src/compiler/parse/errors.ts         | 109 +++++++++++++++++++++++++++
 src/compiler/parse/index.ts          |  16 +---
 src/compiler/parse/read/script.ts    |  20 ++---
 src/compiler/parse/read/style.ts     |  30 ++------
 src/compiler/parse/state/mustache.ts |  33 ++++----
 7 files changed, 144 insertions(+), 72 deletions(-)
 create mode 100644 src/compiler/parse/errors.ts

diff --git a/package-lock.json b/package-lock.json
index 4e9e06824a..193784692e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4329,9 +4329,9 @@
       "dev": true
     },
     "typescript": {
-      "version": "3.5.3",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.5.3.tgz",
-      "integrity": "sha512-ACzBtm/PhXBDId6a6sDJfroT2pOWt/oOnk4/dElG5G33ZL776N3Y6/6bKZJBFpd+b05F3Ct9qDjMeJmRWtE2/g==",
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.0.2.tgz",
+      "integrity": "sha512-e4ERvRV2wb+rRZ/IQeb3jm2VxBsirQLpQhdxplZ2MEzGvDkkMmPglecnNDfSUBivMjP93vRbngYYDQqQ/78bcQ==",
       "dev": true
     },
     "uri-js": {
diff --git a/package.json b/package.json
index 36453769e6..bc32f287be 100644
--- a/package.json
+++ b/package.json
@@ -91,7 +91,7 @@
     "source-map-support": "^0.5.13",
     "tiny-glob": "^0.2.6",
     "tslib": "^1.10.0",
-    "typescript": "^3.5.3"
+    "typescript": "^4.0.2"
   },
   "nyc": {
     "include": [
diff --git a/src/compiler/parse/errors.ts b/src/compiler/parse/errors.ts
new file mode 100644
index 0000000000..3f2f8a711e
--- /dev/null
+++ b/src/compiler/parse/errors.ts
@@ -0,0 +1,109 @@
+interface ErroMessage {
+	/**
+	 * The short code that references this error
+	 */
+	code: string;
+	/**
+	 * A friendly error message that will be displayed to the user
+	 */
+	message: string;
+}
+
+/**
+ * Generates an error message for a given parsing error.
+ * 
+ * Returns an object containing the error code and an actionable message
+ */
+type error_generator = (...args: string[]) => ErroMessage;
+
+export const template_errors: Record<string, error_generator> = {
+	duplicate_style: () => ({
+		code: 'duplicate-style',
+		message: 'You can only have one top-level <style> tag per component'
+	}),
+	duplicate_instance_script: () => ({
+		code: `invalid-script`,
+		message: `A component can only have one instance-level <script> element`
+	}),
+	duplicate_module_script: () => ({
+		code: `invalid-script`,
+		message: `A component can only have one <script context="module"> element`
+	}),
+	dynamic_context_attribute: () => ({
+		code: 'invalid-script',
+		message: `context attribute must be static`
+	}),
+	fixed_context_attribute: () => ({
+		code: `invalid-script`,
+		message: `If the context attribute is supplied, its value must be "module"`
+	}),
+	invalid_elseif: () => ({
+		code: 'invalid-elseif',
+		message: `'elseif' should be 'else if'`
+	}),
+	else_if_without_if: () => ({
+		code: `invalid-elseif-placement`,
+		message: `Cannot have an {:else if ...} block outside an {#if ...} block`
+	}),
+	else_if_before_block_close: (block) => ({
+		code: `invalid-elseif-placement`,
+		message: `Expected to close ${block} before seeing {:else if ...} block`
+	}),
+	else_without_if_each: () => ({
+		code: `invalid-elseif-placement`,
+		message: `Cannot have an {:else} block outside an {#if ...} or {#each ...} block`
+	}),
+	else_before_block_close: (block) => ({
+		code: `invalid-elseif-placement`,
+		message: `Expected to close ${block} before seeing {:else} block`
+	}),
+
+	unexpected_block_close: () => ({
+		code: `unexpected-block-close`,
+		message: `Unexpected block closing tag`
+	}),
+	
+	unclosed_script: () => ({
+		code: `unclosed-script`,
+		message: `<script> must have a closing tag`
+	}),
+	unclosed_style: () => ({
+		code: `unclosed-style`,
+		message: `<style> must have a closing tag`
+	}),
+	unclosed_comment: () => ({
+		code: `unclosed-comment`,
+		message: `comment was left open, expected -->`
+	}),
+	unexpected_token: () => ({
+		code: 'unexpected-token',
+		message: 'Expected )'
+	})
+};
+
+export const css_errors: Record<string, error_generator> = {
+	invalid_ref_selector: () => ({
+		code: `invalid-ref-selector`,
+		message: 'ref selectors are no longer supported'
+	}),
+	invalid_declaration: () => ({
+		code: `invalid-declaration`,
+		message: `Declaration cannot be empty`
+	}),
+	empty_global_selector: () => ({
+		code: `css-syntax-error`,
+		message: `:global() must contain a selector`
+	}),
+	syntax_error: (message) => ({
+		code: `css-syntax-error`,
+		message
+	})
+};
+
+export const js_errors: Record<string, error_generator> = {
+	invalid_ref_selector: () => ({
+		code: `invalid-ref-selector`,
+		message: 'ref selectors are no longer supported'
+	})
+};
+
diff --git a/src/compiler/parse/index.ts b/src/compiler/parse/index.ts
index f378fced41..f92b4ae0ab 100644
--- a/src/compiler/parse/index.ts
+++ b/src/compiler/parse/index.ts
@@ -5,6 +5,7 @@ import { reserved } from '../utils/names';
 import full_char_code_at from '../utils/full_char_code_at';
 import { TemplateNode, Ast, ParserOptions, Fragment, Style, Script } from '../interfaces';
 import error from '../utils/error';
+import errors from './errors';
 
 type ParserState = (parser: Parser) => (ParserState | void);
 
@@ -217,27 +218,18 @@ export default function parse(
 	// TODO we may want to allow multiple <style> tags —
 	// one scoped, one global. for now, only allow one
 	if (parser.css.length > 1) {
-		parser.error({
-			code: 'duplicate-style',
-			message: 'You can only have one top-level <style> tag per component'
-		}, parser.css[1].start);
+		parser.error(errors.duplicate_style(), parser.css[1].start);
 	}
 
 	const instance_scripts = parser.js.filter(script => script.context === 'default');
 	const module_scripts = parser.js.filter(script => script.context === 'module');
 
 	if (instance_scripts.length > 1) {
-		parser.error({
-			code: `invalid-script`,
-			message: `A component can only have one instance-level <script> element`
-		}, instance_scripts[1].start);
+		parser.error(errors.duplicate_instance_script(), instance_scripts[1].start);
 	}
 
 	if (module_scripts.length > 1) {
-		parser.error({
-			code: `invalid-script`,
-			message: `A component can only have one <script context="module"> element`
-		}, module_scripts[1].start);
+		parser.error(errors.duplicate_module_script(), module_scripts[1].start);
 	}
 
 	return {
diff --git a/src/compiler/parse/read/script.ts b/src/compiler/parse/read/script.ts
index 6a719250ef..d1b415e01a 100644
--- a/src/compiler/parse/read/script.ts
+++ b/src/compiler/parse/read/script.ts
@@ -2,25 +2,20 @@ import * as acorn from '../acorn';
 import { Parser } from '../index';
 import { Script } from '../../interfaces';
 import { Node, Program } from 'estree';
+import errors from '../errors';
 
 function get_context(parser: Parser, attributes: any[], start: number): string {
 	const context = attributes.find(attribute => attribute.name === 'context');
 	if (!context) return 'default';
 
 	if (context.value.length !== 1 || context.value[0].type !== 'Text') {
-		parser.error({
-			code: 'invalid-script',
-			message: `context attribute must be static`
-		}, start);
+		parser.error(errors.dynamic_context_attribute(), start);
 	}
 
 	const value = context.value[0].data;
 
 	if (value !== 'module') {
-		parser.error({
-			code: `invalid-script`,
-			message: `If the context attribute is supplied, its value must be "module"`
-		}, context.start);
+		parser.error(errors.fixed_context_attribute(), context.start);
 	}
 
 	return value;
@@ -28,13 +23,10 @@ function get_context(parser: Parser, attributes: any[], start: number): string {
 
 export default function read_script(parser: Parser, start: number, attributes: Node[]): Script {
 	const script_start = parser.index;
-	const error_message ={
-		code: `unclosed-script`,
-		message: `<script> must have a closing tag`
-	};
-	const [data, matched] = parser.read_until(/<\/script\s*>/, error_message);
 
-	if (!matched) parser.error(error_message);
+	const [data, matched] = parser.read_until(/<\/script\s*>/, errors.unclosed_script());
+
+	if (!matched) parser.error(errors.unclosed_script());
 
 	const source = parser.template.slice(0, script_start).replace(/[^\n]/g, ' ') + data;
 	
diff --git a/src/compiler/parse/read/style.ts b/src/compiler/parse/read/style.ts
index b4500b0454..46dcb02954 100644
--- a/src/compiler/parse/read/style.ts
+++ b/src/compiler/parse/read/style.ts
@@ -3,17 +3,15 @@ import { walk } from 'estree-walker';
 import { Parser } from '../index';
 import { Node } from 'estree';
 import { Style } from '../../interfaces';
+import { css_errors, template_errors } from '../errors';
 
 export default function read_style(parser: Parser, start: number, attributes: Node[]): Style {
 	const content_start = parser.index;
-	const error_message ={
-		code: `unclosed-style`,
-		message: `<style> must have a closing tag`
-	};
-	const [styles, matched] = parser.read_until(/<\/style\s*>/, error_message);
+
+	const [styles, matched] = parser.read_until(/<\/style\s*>/, template_errors.unclosed_style());
 	const content_end = parser.index;
 
-	if (!matched) parser.error(error_message);
+	if (!matched) parser.error(template_errors.unclosed_style());
 
 	let ast;
 
@@ -24,10 +22,7 @@ export default function read_style(parser: Parser, start: number, attributes: No
 		});
 	} catch (err) {
 		if (err.name === 'CssSyntaxError') {
-			parser.error({
-				code: `css-syntax-error`,
-				message: err.message
-			}, err.offset);
+			parser.error(css_errors.syntax_error(err.message), err.offset);
 		} else {
 			throw err;
 		}
@@ -45,26 +40,17 @@ export default function read_style(parser: Parser, start: number, attributes: No
 					const b = node.children[i + 1];
 
 					if (is_ref_selector(a, b)) {
-						parser.error({
-							code: `invalid-ref-selector`,
-							message: 'ref selectors are no longer supported'
-						}, a.loc.start.offset);
+						parser.error(css_errors.invalid_ref_selector(), a.loc.start.offset);
 					}
 				}
 			}
 
 			if (node.type === 'Declaration' && node.value.type === 'Value' && node.value.children.length === 0) {
-				parser.error({
-					code: `invalid-declaration`,
-					message: `Declaration cannot be empty`
-				}, node.start);
+				parser.error(css_errors.invalid_declaration(), node.start);
 			}
 
 			if (node.type === 'PseudoClassSelector' && node.name === 'global' && node.children === null) {
-				parser.error({
-					code: `css-syntax-error`,
-					message: `:global() must contain a selector`
-				}, node.loc.start.offset);
+				parser.error(css_errors.empty_global_selector(), node.loc.start.offset);
 			}
 
 			if (node.loc) {
diff --git a/src/compiler/parse/state/mustache.ts b/src/compiler/parse/state/mustache.ts
index dc26d994df..38cef69533 100644
--- a/src/compiler/parse/state/mustache.ts
+++ b/src/compiler/parse/state/mustache.ts
@@ -6,6 +6,7 @@ import { trim_start, trim_end } from '../../utils/trim';
 import { to_string } from '../utils/node';
 import { Parser } from '../index';
 import { TemplateNode } from '../../interfaces';
+import { template_errors } from '../errors';
 
 function trim_whitespace(block: TemplateNode, trim_before: boolean, trim_after: boolean) {
 	if (!block.children || block.children.length === 0) return; // AwaitBlock
@@ -64,10 +65,7 @@ export default function mustache(parser: Parser) {
 		} else if (block.type === 'AwaitBlock') {
 			expected = 'await';
 		} else {
-			parser.error({
-				code: `unexpected-block-close`,
-				message: `Unexpected block closing tag`
-			});
+			parser.error(template_errors.unexpected_block_close());
 		}
 
 		parser.eat(expected, true);
@@ -96,10 +94,7 @@ export default function mustache(parser: Parser) {
 		parser.stack.pop();
 	} else if (parser.eat(':else')) {
 		if (parser.eat('if')) {
-			parser.error({
-				code: 'invalid-elseif',
-				message: `'elseif' should be 'else if'`
-			});
+			parser.error(template_errors.invalid_elseif());
 		}
 
 		parser.allow_whitespace();
@@ -108,12 +103,11 @@ export default function mustache(parser: Parser) {
 		if (parser.eat('if')) {
 			const block = parser.current();
 			if (block.type !== 'IfBlock') {
-				parser.error({
-					code: `invalid-elseif-placement`,
-					message: parser.stack.some(block => block.type === 'IfBlock')
-						? `Expected to close ${to_string(block)} before seeing {:else if ...} block`
-						: `Cannot have an {:else if ...} block outside an {#if ...} block`
-				});
+				parser.error(
+					parser.stack.some(block => block.type === 'IfBlock') 
+						? template_errors.else_if_before_block_close(to_string(block)) 
+						: template_errors.else_if_without_if()
+				);
 			}
 
 			parser.require_whitespace();
@@ -146,12 +140,11 @@ export default function mustache(parser: Parser) {
 		else {
 			const block = parser.current();
 			if (block.type !== 'IfBlock' && block.type !== 'EachBlock') {
-				parser.error({
-					code: `invalid-else-placement`,
-					message: parser.stack.some(block => block.type === 'IfBlock' || block.type === 'EachBlock')
-						? `Expected to close ${to_string(block)} before seeing {:else} block`
-						: `Cannot have an {:else} block outside an {#if ...} or {#each ...} block`
-				});
+				parser.error(
+					parser.stack.some(block => block.type === 'IfBlock' || block.type === 'EachBlock') 
+						? template_errors.else_before_block_close(to_string(block)) 
+						: template_errors.else_without_if()
+				);
 			}
 
 			parser.allow_whitespace();