diff options
-rw-r--r-- | src/util/html.js | 70 |
1 files changed, 63 insertions, 7 deletions
diff --git a/src/util/html.js b/src/util/html.js index 5ea5e0ad..a7b44ec6 100644 --- a/src/util/html.js +++ b/src/util/html.js @@ -369,7 +369,9 @@ export function template(getContent) { export class Template { #tag = new Tag(); + #slotContents = {}; + #slotTraces = {}; constructor(getContent) { this.#prepareContent(getContent); @@ -394,6 +396,7 @@ export class Template { } else { this.#slotContents[slotName] = [content]; } + this.#slotTraces[slotName] = getTopOfCallerTrace(); } getSlot(slotName) { @@ -409,6 +412,11 @@ export class Template { } } + // Dragons. + getSlotTrace(slotName) { + return this.#slotTraces[slotName] ?? ''; + } + set content(_value) { throw new Error(`Template content can't be changed after constructed`); } @@ -422,10 +430,21 @@ export class Template { } } +function getTopOfCallerTrace() { + const error = new Error(); + return error.stack.split('\n') + .find(line => line.includes('at ') && !line.includes('/util/html.js')) + .replace('at ', '') + .trim(); +} + export class Slot { #defaultTag = new Tag(); #handleContent = null; + #stackIdentifier = ''; + #stackTrace = ''; + constructor(template, slotName, defaultContentOrHandleContent) { if (!template) { throw new Error(`Expected template`); @@ -438,6 +457,8 @@ export class Slot { this.template = template; this.slotName = slotName; + this.#setupStackMutation(); + if (typeof defaultContentOrHandleContent === 'function') { this.#handleContent = defaultContentOrHandleContent; } else { @@ -445,6 +466,36 @@ export class Slot { } } + #setupStackMutation() { + // Here be dragons. + + this.#stackIdentifier = `Slot.valueOf:${Math.floor(10000000 * Math.random())}`; + + this.valueOf = () => this.constructor.prototype.valueOf.apply(this); + Object.defineProperty(this.valueOf, 'name', { + value: this.#stackIdentifier, + }); + + this.#stackTrace = getTopOfCallerTrace(); + } + + #mutateStack(error) { + // Splice the line marked with #stackIdentifier with a more descriptive message, + // and erase the line above as well because it's the trace for the constructor's + // valueOf(). + const lines = error.stack.split('\n'); + const index = lines.findIndex(line => line.includes(`at ${this.#stackIdentifier}`)) + const setTrace = this.template.getSlotTrace(this.slotName); + console.log('index:', index); + lines.splice( + index - 1, 2, + `at Slot("${this.slotName}") (from ${this.#stackTrace})`, + (setTrace + ? `at …set from ${setTrace}` + : `at …left unset`)); + error.stack = lines.join('\n'); + } + set defaultContent(value) { this.#defaultTag.content = value; } @@ -470,14 +521,19 @@ export class Slot { } valueOf() { - if (this.#handleContent) { - const result = this.#handleContent(this.content); - if (result === null || result === undefined) { - throw new Error(`Expected function for slot ${this.slotName} to return a value, got ${result}`); + try { + if (this.#handleContent) { + const result = this.#handleContent(this.content); + if (result === null || result === undefined) { + throw new Error(`Expected function for slot ${this.slotName} to return a value, got ${result}`); + } + return result.valueOf(); + } else { + return this.content.valueOf(); } - return result.valueOf(); - } else { - return this.content.valueOf(); + } catch (error) { + this.#mutateStack(error); + throw error; } } } |