Refactor recursive build mechanism

font-src/support/glyph-block.mjs

@@ -1,6 +1,69 @@
+export class RecursiveBuildFilter {
+	constructor(glyphIdFilter) {
+		this.glyphIdFilter = glyphIdFilter;
+	}
+	glyphIsNeeded(id) {
+		return this.glyphIdFilter.has(id);
+	}
+}
+
+export class DependencyManager {
+	constructor() {
+		this.glyphToGlyph = new WeakMap();
+		this.glyphToBlock = new WeakMap();
+	}
+	addDependency(dependent, dependency) {
+		let s = this.glyphToGlyph.get(dependent);
+		if (!s) {
+			s = new Set();
+			this.glyphToGlyph.set(dependent, s);
+		}
+		s.add(dependency);
+	}
+	traverseDependencies(glyphs) {
+		let state = new Map();
+		const PENDING = 1,
+			CHECKED = 2;
+		for (const glyph of glyphs) state.set(glyph, PENDING);
+
+		for (;;) {
+			let found = false;
+			for (const [glyph, s] of state) {
+				if (s !== PENDING) continue;
+				const deps = this.glyphToGlyph.get(glyph);
+				if (deps) {
+					for (const g of deps) state.set(g, PENDING);
+					found = true;
+				}
+				state.set(glyph, CHECKED);
+			}
+			if (!found) break;
+		}
+
+		let glyphIdFilter = new Set();
+		for (const g of state.keys()) {
+			if (g.identifier) glyphIdFilter.add(g.identifier);
+		}
+		return new RecursiveBuildFilter(glyphIdFilter);
+	}
+}
+
+export class GlyphBlockExecState {
+	constructor() {
+		this.currentBlockName = null;
+		this.dependencyManager = new DependencyManager();
+	}
+	setGlyphToBlockDependency(glyph) {
+		if (this.currentBlockName) {
+			this.dependencyManager.glyphToBlock.set(glyph, this.currentBlockName);
+		}
+	}
+}
+
 export class GlyphBlock {
-	constructor(capture, blockName, body) {
+	constructor(capture, execState, blockName, body) {
 		this.capture = capture;
+		this.execState = execState;
 		this.blockName = blockName;
 		this.body = body;
 		this.resolved = false;
@@ -8,6 +71,10 @@ export class GlyphBlock {
 	}
 	resolve() {
 		if (this.resolved) return this.exports;
+
+		const prevBlockName = this.execState.currentBlockName;
+		this.execState.currentBlockName = this.blockName;
+
 		this.resolved = true;
 		const pendingApplications = [];
 		const ExportCapture = fnObj => {
@@ -19,6 +86,8 @@ export class GlyphBlock {
 		};
 		this.body(this.capture, ExportCapture);
 		for (const f of pendingApplications) f();
+
+		this.execState.currentBlockName = prevBlockName;
 		return this.exports;
 	}
 }