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silverbullet/common/tree.ts

142 lines
3.2 KiB
TypeScript

export type ParseTree = {
type?: string; // undefined === text node
from?: number;
to?: number;
text?: string;
children?: ParseTree[];
// Only present after running addParentPointers
parent?: ParseTree;
};
export function addParentPointers(tree: ParseTree) {
if (!tree.children) {
return;
}
for (let child of tree.children) {
if (child.parent) {
// Already added parent pointers before
return;
}
child.parent = tree;
addParentPointers(child);
}
}
export function removeParentPointers(tree: ParseTree) {
delete tree.parent;
if (!tree.children) {
return;
}
for (let child of tree.children) {
removeParentPointers(child);
}
}
export function findParentMatching(
tree: ParseTree,
matchFn: (tree: ParseTree) => boolean
): ParseTree | null {
let node = tree.parent;
while (node) {
if (matchFn(node)) {
return node;
}
node = node.parent;
}
return null;
}
export function collectNodesOfType(
tree: ParseTree,
nodeType: string
): ParseTree[] {
return collectNodesMatching(tree, (n) => n.type === nodeType);
}
export function collectNodesMatching(
tree: ParseTree,
matchFn: (tree: ParseTree) => boolean
): ParseTree[] {
if (matchFn(tree)) {
return [tree];
}
let results: ParseTree[] = [];
if (tree.children) {
for (let child of tree.children) {
results = [...results, ...collectNodesMatching(child, matchFn)];
}
}
return results;
}
// return value: returning undefined = not matched, continue, null = delete, new node = replace
export function replaceNodesMatching(
tree: ParseTree,
substituteFn: (tree: ParseTree) => ParseTree | null | undefined
) {
if (tree.children) {
let children = tree.children.slice();
for (let child of children) {
let subst = substituteFn(child);
if (subst !== undefined) {
let pos = tree.children.indexOf(child);
if (subst) {
tree.children.splice(pos, 1, subst);
} else {
// null = delete
tree.children.splice(pos, 1);
}
} else {
replaceNodesMatching(child, substituteFn);
}
}
}
}
export function findNodeMatching(
tree: ParseTree,
matchFn: (tree: ParseTree) => boolean
): ParseTree | null {
return collectNodesMatching(tree, matchFn)[0];
}
export function findNodeOfType(
tree: ParseTree,
nodeType: string
): ParseTree | null {
return collectNodesMatching(tree, (n) => n.type === nodeType)[0];
}
// Finds non-text node at position
export function nodeAtPos(tree: ParseTree, pos: number): ParseTree | null {
if (pos < tree.from! || pos > tree.to!) {
return null;
}
if (!tree.children) {
return tree;
}
for (let child of tree.children) {
let n = nodeAtPos(child, pos);
if (n && n.text !== undefined) {
// Got a text node, let's return its parent
return tree;
} else if (n) {
// Got it
return n;
}
}
return null;
}
// Turn ParseTree back into text
export function renderToText(tree: ParseTree): string {
let pieces: string[] = [];
if (tree.text !== undefined) {
return tree.text;
}
for (let child of tree.children!) {
pieces.push(renderToText(child));
}
return pieces.join("");
}