/******************************************************************************
* Copyright 2023 TypeFox GmbH
* This program and the accompanying materials are made available under the
* terms of the MIT License, which is available in the project root.
******************************************************************************/
import { GrammarAST, GrammarUtils } from 'langium';
import { expandToStringLF, expandToStringLFWithNL } from 'langium/generate';
import type { FakeSVG } from 'railroad-diagrams';
import { default as rr } from 'railroad-diagrams';
export const defaultCss = `
svg.railroad-diagram {
background-color: hsl(30,20%,95%);
}
svg.railroad-diagram path {
stroke-width: 3;
stroke: black;
fill: rgba(0,0,0,0);
}
svg.railroad-diagram text {
font: bold 14px monospace;
text-anchor: middle;
}
svg.railroad-diagram text.label {
text-anchor: start;
}
svg.railroad-diagram text.comment {
font: italic 12px monospace;
}
svg.railroad-diagram rect {
stroke-width: 3;
stroke: black;
fill: hsl(120,100%,90%);
}
`.trim();
export interface GrammarDiagramOptions {
css?: string;
javascript?: string;
}
function styling(options?: GrammarDiagramOptions) {
return expandToStringLF`
${options?.css ? expandToStringLF`
` : ''}
`;
}
/**
* Creates a whole HTML file that contains all railroad diagrams.
*
* @param grammar
* @param options
* Use to add additional styling to all diagrams and additional behavior for the created HTML.
*
* @returns A complete HTML document containing all diagrams.
*/
export function createGrammarDiagramHtml(rules: GrammarAST.ParserRule[], options?: GrammarDiagramOptions): string {
return expandToStringLFWithNL`
${styling(options)}${options?.javascript ? `
` : ''}
${createGrammarDiagram(rules)}
`;
}
/**
* Creates a standalone SVG diagram for each non-terminal of grammar.
*
* @param grammar
* @param options
* Use to add additional styling to all diagrams.
*
* @returns diagrams
* For the rule named 'NonTerminal', diagrams.get('NonTerminal') has its SVG content.
*/
export function createGrammarDiagramSvg(rules: GrammarAST.ParserRule[], options?: GrammarDiagramOptions): Map {
const diagrams = new Map();
const style = styling(options);
for (const nonTerminal of rules) {
const ruleDiagram = new rr.Diagram(toRailroad(nonTerminal.definition));
ruleDiagram.attrs.xmlns = 'http://www.w3.org/2000/svg';
ruleDiagram.children =
ruleDiagram.children.concat(style);
diagrams.set(nonTerminal.name, ruleDiagram.toString());
}
return diagrams;
}
export function createGrammarDiagram(rules: GrammarAST.ParserRule[]): string {
const text: string[] = [];
for (const nonTerminal of rules) {
text.push('', nonTerminal.name, '
', '\n', createRuleDiagram(nonTerminal));
}
return text.join('');
}
function createRuleDiagram(rule: GrammarAST.ParserRule): string {
const diagram = new rr.Diagram(toRailroad(rule.definition));
return diagram.toString();
}
function toRailroad(element: GrammarAST.AbstractElement): FakeSVG[] {
if (GrammarAST.isAssignment(element)) {
return wrapCardinality(element.cardinality, toRailroad(element.terminal));
} else if (GrammarAST.isAlternatives(element)) {
return wrapCardinality(element.cardinality, new rr.Choice(0, element.elements.flatMap(e => toRailroad(e))));
} else if (GrammarAST.isUnorderedGroup(element)) {
const choice = new rr.Choice(0, element.elements.flatMap(e => toRailroad(e)));
const repetition = new rr.ZeroOrMore(choice);
return wrapCardinality(element.cardinality, repetition);
} else if (GrammarAST.isGroup(element)) {
return wrapCardinality(element.cardinality, new rr.Sequence(element.elements.flatMap(e => toRailroad(e))));
} else if (GrammarAST.isKeyword(element)) {
return wrapCardinality(element.cardinality, new rr.Terminal(element.value));
} else if (GrammarAST.isRuleCall(element)) {
return wrapCardinality(element.cardinality, new rr.NonTerminal(element.rule.$refText));
} else if (GrammarAST.isCrossReference(element)) {
if (GrammarAST.isKeyword(element.terminal)) {
return wrapCardinality(element.cardinality, new rr.Terminal(element.terminal.value));
} else if (GrammarAST.isRuleCall(element.terminal)) {
return wrapCardinality(element.cardinality, new rr.NonTerminal(element.terminal.rule.$refText));
} else {
const nameAssignment = element.type.ref && GrammarUtils.findNameAssignment(element.type.ref);
if (nameAssignment) {
return wrapCardinality(element.cardinality, toRailroad(nameAssignment));
} else {
return wrapCardinality(element.cardinality, new rr.NonTerminal('UNKNOWN'));
}
}
} else {
return [];
}
}
function wrapCardinality(cardinality: '?' | '*' | '+' | undefined, items: FakeSVG | FakeSVG[]): FakeSVG[] {
items = Array.isArray(items) ? items : [items];
if (cardinality) {
if (cardinality === '*') {
return [new rr.ZeroOrMore(new rr.Sequence(items))];
} else if (cardinality === '+') {
return [new rr.OneOrMore(new rr.Sequence(items))];
} else if (cardinality === '?') {
return [new rr.Optional(new rr.Sequence(items))];
}
}
return items;
}