Skip to content

chore: reworked how the underlying expressions-type system works #1391

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Nov 30, 2025
Merged

chore: reworked how the underlying expressions-type system works #1391

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
013a078
reworked how the underlying expressions-type system works
CommanderStorm Nov 29, 2025
0c90f96
fix typo
CommanderStorm Nov 30, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
99 changes: 84 additions & 15 deletions build/generate-docs.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,23 +4,28 @@ import {formatJSON} from './util';

/**
* This script generates markdown documentation from the JSON schema.
* It leverages exitsing md files in the docs folder and adds generated files from the v8.json file.
* It leverages existing md files in the docs folder and adds generated files from the v8.json file.
*/

const BASE_PATH = 'docs';

type JsonExpressionSyntax = {
overloads: {
parameters: string[];
'output-type': string;
}[];
parameters?: {
name: string;
type: string;
doc?: string;
'output-type': string | string[];
}[];
parameters?: Parameter[];
}

type Parameter ={
name: string;
type: ParameterType;
doc?: string;
};

// either a basic type, a union of a few basic types or an object
type ParameterType = string | string[] | { [key: string]: JsonObject };

type JsonSdkSupport = {
[info: string]: {
js?: string;
Expand All @@ -36,10 +41,13 @@ type JsonObject = {
type: string;
doc: string;
requires?: any[];
example: string | object | number;
example: string | object | number | boolean;
expression?: { interpolated?: boolean; parameters?: string[]};
transition?: boolean;
// for enum type: what is the type of the emum elements
values?: {[key: string]: { doc: string; 'sdk-support'?: JsonSdkSupport }} | number[];
// for array type: what is the type of the array elements?
value?: string;
minimum?: number;
maximum?: number;
}
Expand Down Expand Up @@ -121,6 +129,52 @@ function sdkSupportToMarkdown(support: JsonSdkSupport): string {
return markdown;
}

/**
* Joins the array of type strings into a single string with `" | "` between them.
* @param input the array or string to be joined
* @returns the joined string
*/
function parameterTypeToType(input: ParameterType):string{
if ( typeof input === 'string' )
return input
if (Array.isArray(input)) {
return input.join(' | ')
}
const parameters = Object.entries(input)
.map(([key, val])=> {
const requiredSuffix = val.required ? '' : '?';
return `${key}${requiredSuffix}: ${jsonObjectToType(val)}`
})
.join(', ')

return `{${parameters}}`;
}

/**
* Converts the JSON object to a type string.
* @param val - the JSON object
* @returns the type string
*/
function jsonObjectToType(val: JsonObject):string{
switch (val.type) {
case 'boolean':
case 'string':
case 'number':
case 'color':
// basic types -> no conversion needed
return val.type
case 'array':
return `${val.type}<${parameterTypeToType(val.value)}>`;
case 'enum':
const values = val.values;
if (!values || Array.isArray(values))
throw new Error(`Enum ${JSON.stringify(val)} has no "values" describing the contained Options in the form of an Object`)
return Object.keys(values).map(s=>`"${s}"`).join(' | ');
default:
throw new Error(`Unknown "type" ${val.type} for ${JSON.stringify(val)}`)
}
}

/**
* Converts the expression syntax object to markdown format.
* @param key - the expression name
Expand All @@ -130,17 +184,32 @@ function sdkSupportToMarkdown(support: JsonSdkSupport): string {
function expressionSyntaxToMarkdown(key: string, syntax: JsonExpressionSyntax) {
let markdown = '\nSyntax:\n';
const codeBlockLines = syntax.overloads.map((overload) => {
return `[${[`"${key}"`, ...overload.parameters].join(', ')}]: ${overload['output-type']}`;
const key_and_parameters = [`"${key}"`, ...overload.parameters].join(', ');

return `[${key_and_parameters}]: ${parameterTypeToType(overload['output-type'])}`;
});
markdown += `${codeBlockMarkdown(codeBlockLines.join('\n'), 'js')}\n`;
for (const parameter of syntax.parameters ?? []) {
markdown += `- \`${parameter.name}\``;
if (parameter.type) {
const type = parameter.type.replaceAll('<', '&lt;').replaceAll('>', '&gt;');
markdown += `: *${type}*`;
}
const type = parameterTypeToType(parameter.type).replaceAll('<', '&lt;').replaceAll('>', '&gt;');
markdown += `- \`${parameter.name}\`: \`${type}\``;
if (parameter.doc) {
markdown += ` — ${parameter.doc}`;
markdown += `- ${parameter.doc}`;
}
if (typeof parameter.type !== 'string' && !Array.isArray(parameter.type)){
// the type is an object type => we can attach more documentation about the contained variables
markdown += ' \nParameters:'
Object.entries(parameter.type).forEach(([key, val])=>{
const type = jsonObjectToType(val).replaceAll('<', '&lt;').replaceAll('>', '&gt;');
markdown += `\n - \`${key}\`: \`${type}\` - ${val.doc}`
if (val.type==='enum' && val.values){
markdown += ' \n Possible values are:'
for (const [enumKey, enumValue] of Object.entries(val.values)) {
const defaultIndicator = val.default === enumKey ? ' *default*' : '';
markdown += `\n - \`"${enumKey}"\`${defaultIndicator} - ${enumValue.doc}`
}
}

})
}
markdown += '\n';
}
Expand Down
116 changes: 95 additions & 21 deletions src/reference/v8.json
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3053,7 +3053,7 @@
},
{
"name": "type",
"type": "\"string\" | \"number\" | \"boolean\"",
"type": ["string", "number", "boolean"],
"doc": "The asserted type of the input array."
},
{
Expand Down Expand Up @@ -3295,12 +3295,12 @@
"parameters": [
{
"name": "input",
"type": "string | number",
"type": ["string", "number"],
"doc": "Any expression."
},
{
"name": "label_i",
"type": "string literal | number literal | array<string literal> | array<number literal>",
"type": ["string literal", "number literal", "array<string literal>", "array<number literal>"],
"doc": "The i-th literal value or array of literal values to match the input against."
},
{
Expand Down Expand Up @@ -3399,13 +3399,13 @@
"overloads": [
{
"parameters": ["interpolation_type", "input", "stop_1_input", "stop_1_output", "...", "stop_n_input", "stop_n_output"],
"output-type": "number | array<number> | color | array<color> | projection"
"output-type": ["number", "array<number>", "color", "array<color>", "projection"]
}
],
"parameters": [
{
"name": "interpolation_type",
"type": "[\"linear\"] | [\"exponential\", base] | [\"cubic-bezier\", x1, y1, x2, y2]",
"type": ["[\"linear\"]", "[\"exponential\", base]", "[\"cubic-bezier\", x1, y1, x2, y2]"],
"doc": "The interpolation type."
},
{
Expand All @@ -3420,7 +3420,7 @@
},
{
"name": "stop_i_output",
"type": "number | array<number> | color | array<color> | projection",
"type": ["number", "array<number>", "color", "array<color>", "projection"],
"doc": "The output value corresponding to the i-th stop."
}
]
Expand All @@ -3441,13 +3441,13 @@
"overloads": [
{
"parameters": ["interpolation_type", "input", "stop_1_input", "stop_1_output", "...", "stop_n_input", "stop_n_output"],
"output-type": "color | array<color>"
"output-type": ["color", "array<color>"]
}
],
"parameters": [
{
"name": "interpolation_type",
"type": "[\"linear\"] | [\"exponential\", base] | [\"cubic-bezier\", x1, y1, x2, y2]"
"type": ["[\"linear\"]", "[\"exponential\", base]", "[\"cubic-bezier\", x1, y1, x2, y2]"]
Copy link
Member Author

@CommanderStorm CommanderStorm Nov 30, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

this should likely be documented as a array with one syntax enum in it.
Still fairly messy as-is.

Different PR though.

},
{
"name": "input",
Expand All @@ -3459,7 +3459,7 @@
},
{
"name": "stop_i_output",
"type": "color | array<color>"
"type": ["color", "array<color>"]
}
]
},
Expand All @@ -3479,13 +3479,13 @@
"overloads": [
{
"parameters": ["interpolation_type", "input", "stop_1_input", "stop_1_output", "...", "stop_n_input", "stop_n_output"],
"output-type": "color | array<color>"
"output-type": ["color", "array<color>"]
}
],
"parameters": [
{
"name": "interpolation_type",
"type": "[\"linear\"] | [\"exponential\", base] | [\"cubic-bezier\", x1, y1, x2, y2]"
"type": ["[\"linear\"]", "[\"exponential\", base]", "[\"cubic-bezier\", x1, y1, x2, y2]"]
},
{
"name": "input",
Expand All @@ -3497,7 +3497,7 @@
},
{
"name": "stop_i_output",
"type": "color | array<color>"
"type": ["color", "array<color>"]
}
]
},
Expand Down Expand Up @@ -3702,7 +3702,7 @@
}
},
"collator": {
"doc": "Returns a `collator` for use in locale-dependent comparison operations. The `case-sensitive` and `diacritic-sensitive` options default to `false`. The `locale` argument specifies the IETF language tag of the locale to use. If none is provided, the default locale is used. If the requested locale is not available, the `collator` will use a system-defined fallback locale. Use `resolved-locale` to test the results of locale fallback behavior.",
"doc": "Returns a `collator` for use in locale-dependent comparison operations. Use `resolved-locale` to test the results of locale fallback behavior.",
"syntax": {
"overloads": [
{
Expand All @@ -3713,7 +3713,25 @@
"parameters": [
{
"name": "options",
"type": "{ \"case-sensitive\"?: boolean, \"diacritic-sensitive\"?: boolean, \"locale\"?: string }"
"type": {
"case-sensitive": {
"type": "boolean",
"default": false,
"example": true,
"doc": "If characters of different case-ness are considered different"
},
"diacritic-sensitive": {
"type": "boolean",
"default": false,
"example": true,
"doc": "If characters with different diacritics are considered different"
},
"locale": {
"type": "string",
"example": "en",
"doc": "IETF language tag of the locale to use. If none is provided, the default locale is used. If the requested locale is not available, the `collator` will use a system-defined fallback locale."
}
}
}
]
},
Expand All @@ -3728,7 +3746,7 @@
}
},
"format": {
"doc": "Returns a `formatted` string for displaying mixed-format text in the `text-field` property. The input may contain a string literal or expression, including an [`'image'`](#image) expression. Strings may be followed by a style override object that supports the following properties:\n\n- `\"text-font\"`: Overrides the font stack specified by the root layout property.\n\n- `\"text-color\"`: Overrides the color specified by the root paint property.\n\n- `\"font-scale\"`: Applies a scaling factor on `text-size` as specified by the root layout property.\n\n- `\"vertical-align\"`: Aligns vertically text section or image in relation to the row it belongs to. Possible values are: \n\t- `\"bottom\"` *default*: align the bottom of this section with the bottom of other sections.\n<img alt=\"Visual representation of bottom alignment\" src=\"https://github.com/user-attachments/assets/0474a2fd-a4b2-417c-9187-7a13a28695bc\"/>\n\t- `\"center\"`: align the center of this section with the center of other sections.\n<img alt=\"Visual representation of center alignment\" src=\"https://github.com/user-attachments/assets/92237455-be6d-4c5d-b8f6-8127effc1950\"/>\n\t- `\"top\"`: align the top of this section with the top of other sections.\n<img alt=\"Visual representation of top alignment\" src=\"https://github.com/user-attachments/assets/45dccb28-d977-4abb-a006-4ea9792b7c53\"/>\n\t- Refer to [the design proposal](https://github.com/maplibre/maplibre-style-spec/issues/832) for more details.\n\n - [Change the case of labels](https://maplibre.org/maplibre-gl-js/docs/examples/change-case-of-labels/)\n\n - [Display and style rich text labels](https://maplibre.org/maplibre-gl-js/docs/examples/display-and-style-rich-text-labels/)",
"doc": "Returns a `formatted` string for displaying mixed-format text in the `text-field` property. The input may contain a string literal or expression, including an [`'image'`](#image) expression. Strings may be followed by a style override object. [Change the case of labels](https://maplibre.org/maplibre-gl-js/docs/examples/change-case-of-labels/)\n\n - [Display and style rich text labels](https://maplibre.org/maplibre-gl-js/docs/examples/display-and-style-rich-text-labels/)",
"syntax": {
"overloads": [
{
Expand All @@ -3739,11 +3757,44 @@
"parameters": [
{
"name": "input_i",
"type": "string | image"
"type": ["string", "image"]
},
{
"name": "style_overrides_i",
"type": "{ \"text-font\"?: string, \"text-color\"?: color, \"font-scale\"?: number, \"vertical-align\"?: \"bottom\" | \"center\" | \"top\" }"
"type": {
"text-font": {
"type": "string",
"doc": "Overrides the font stack specified by the root layout property.",
"example": "Arial Unicode MS Regular"
},
"text-color": {
"type": "color",
"doc": "Overrides the color specified by the root paint property.",
"example": "#333"
},
"font-scale": {
"type": "number",
"doc":"Applies a scaling factor on `text-size` as specified by the root layout property.",
"example": 1.2
},
"vertical-align": {
"type": "enum",
"doc": "Aligns a vertical text section or image in relation to the row it belongs to. Refer to [the design proposal](https://github.com/maplibre/maplibre-style-spec/issues/832) for more details.",
"default": "bottom",
"example": "bottom",
"values": {
"bottom": {
"doc": "align the bottom of this section with the bottom of other sections.\n![Visual representation of bottom alignment](https://github.com/user-attachments/assets/0474a2fd-a4b2-417c-9187-7a13a28695bc)"
},
"center": {
"doc": "align the center of this section with the center of other sections.\n![Visual representation of center alignment](https://github.com/user-attachments/assets/92237455-be6d-4c5d-b8f6-8127effc1950)"
},
"top": {
"doc": "align the top of this section with the top of other sections.\n![Visual representation of top alignment](https://github.com/user-attachments/assets/45dccb28-d977-4abb-a006-4ea9792b7c53)"
}
}
}
}
}
]
},
Expand Down Expand Up @@ -3836,7 +3887,7 @@
}
},
"number-format": {
"doc": "Converts the input number into a string representation using the providing formatting rules. If set, the `locale` argument specifies the locale to use, as a BCP 47 language tag. If set, the `currency` argument specifies an ISO 4217 code to use for currency-style formatting. If set, the `min-fraction-digits` and `max-fraction-digits` arguments specify the minimum and maximum number of fractional digits to include.\n\n - [Display HTML clusters with custom properties](https://maplibre.org/maplibre-gl-js/docs/examples/display-html-clusters-with-custom-properties/)",
"doc": "Converts the input number into a string representation using the provided format_options.\n\n - [Display HTML clusters with custom properties](https://maplibre.org/maplibre-gl-js/docs/examples/display-html-clusters-with-custom-properties/)",
"syntax": {
"overloads": [
{
Expand All @@ -3847,11 +3898,34 @@
"parameters": [
{
"name": "input",
"type": "number"
"type": "number",
"doc": "number to format"
},
{
"name": "format_options",
"type": "{ \"locale\"?: string, \"currency\"?: string, \"min-fraction-digits\"?: number, \"max-fraction-digits\"?: number }"
"type": {
"locale": {
"type": "string",
"example": "en",
"doc": "Specifies the locale to use, as a BCP 47 language tag"
},
"currency": {
"type": "string",
"example": "USD",
"doc": "An ISO 4217 code to use for currency-style formatting"
},
"min-fraction-digits": {
"type": "number",
"example": 1,
"doc": "Minimum number of fractional digits to include"
},
"max-fraction-digits": {
"type": "number",
"example": 2,
"doc": "Maximum number of fractional digits to include"
}
},
"doc": "Format options for the number"
}
]
},
Expand Down Expand Up @@ -4143,7 +4217,7 @@
"parameters": [
{
"name": "array_or_string",
"type": "array | string"
"type": ["array", "string"]
}
]
},
Expand Down