211 lines
8.0 KiB
TypeScript
211 lines
8.0 KiB
TypeScript
import { Reader, Annotated, Dictionary, is, peel, preserves, Record, strip, Tuple, Value, Position, position, ReaderOptions, stringify } from '@preserves/core';
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import { Input, NamedPattern, Pattern, Schema } from './meta';
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import * as M from './meta';
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import { SchemaSyntaxError } from './error';
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const positionTable = new WeakMap<Input & object, Position>();
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export function recordPosition<X extends Input & object>(v: X, pos: Position | null): X {
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if (pos === null) { console.error('Internal error in Schema reader: null source position for', v); }
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if (pos !== null) positionTable.set(v, pos);
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return v;
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}
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export function refPosition(v: Input & object): Position | null {
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return positionTable.get(v) ?? null;
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}
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function splitBy<T>(items: Array<T>, separator: T): Array<Array<T>> {
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const groups: Array<Array<T>> = [];
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let group: Array<T> = [];
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function finish() {
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if (group.length > 0) {
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groups.push(group);
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group = [];
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}
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}
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for (const item of items) {
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if (is(item, separator)) {
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finish();
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} else {
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group.push(item);
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}
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}
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finish();
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return groups;
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}
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function invalidClause(clause: Array<Input>): never {
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throw new SchemaSyntaxError(preserves`Invalid Schema clause: ${clause}`,
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position(clause[0] ?? false));
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}
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function invalidPattern(name: string, item: Input, pos: Position | null): never {
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throw new SchemaSyntaxError(`Invalid pattern in ${name}: ${stringify(item)}`, pos);
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}
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export function readSchema(source: string, options?: ReaderOptions<never>): Schema {
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const toplevelTokens = new Reader<never>(source, { ... options ?? {}, includeAnnotations: true }).readToEnd();
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return parseSchema(toplevelTokens);
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}
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export function parseSchema(toplevelTokens: Array<Input>): Schema {
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const toplevelClauses = splitBy(peel(toplevelTokens) as Array<Input>, M.DOT);
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let version: M.Version | undefined = void 0;
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let pointer: M.PointerName = false;
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let definitions = new Dictionary<Pattern, never>();
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for (const clause of toplevelClauses) {
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if (!Array.isArray(clause)) {
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invalidClause(clause);
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} else if (clause.length >= 2 && is(clause[1], M.EQUALS)) {
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const name = peel(clause[0]);
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if (typeof name !== 'symbol') invalidClause(clause);
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if (!M.isValidToken(name.description!)) {
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throw new SchemaSyntaxError(preserves`Invalid definition name: ${name}`,
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position(clause[0]));
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}
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if (definitions.has(name)) {
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throw new SchemaSyntaxError(preserves`Duplicate definition: ${clause}`,
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position(clause[0]));
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}
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definitions.set(name, parseDefinition(name, clause.slice(2)));
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} else if (clause.length === 2 && is(clause[0], M.$version)) {
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version = M.asVersion(peel(clause[1]));
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} else if (clause.length === 2 && is(clause[0], M.$pointer)) {
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const pos = position(clause[1]);
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const stx = peel(clause[1]);
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const quasiName = 'pointer name specification';
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pointer = M.asPointerName((stx === false) ? stx
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: (typeof stx === 'symbol') ? parseRef(quasiName, pos, stx)
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: invalidPattern(quasiName, stx, pos));
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} else {
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invalidClause(clause);
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}
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}
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if (version === void 0) {
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throw new SchemaSyntaxError("Schema: missing version declaration.", null);
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}
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return M.asSchema(Record(M.$schema, [new Dictionary<Value>([
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[M.$version, version],
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[M.$pointer, pointer],
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[M.$definitions, definitions],
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])]));
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}
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function parseDefinition(name: symbol, body: Array<Input>): Pattern {
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return parseOp(body, M.ORSYM, p => parseOp(p, M.ANDSYM, p => parseBase(name, p)));
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}
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function parseOp(body: Array<Input>, op: Input, k: (p: Array<Input>) => Pattern): Pattern {
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const pieces = splitBy(body, op);
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if (pieces.length === 1) return k(pieces[0]);
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switch (op) {
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case M.ORSYM: return Record(M.$or, [pieces.map(k)]);
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case M.ANDSYM: return Record(M.$and, [pieces.map(k)]);
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default: throw new Error("Internal error: unexpected operator");
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}
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}
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function findName(x: Input): symbol | false {
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if (!Annotated.isAnnotated<never>(x)) return false;
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for (const a0 of x.annotations) {
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const a = peel(a0);
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if (typeof a === 'symbol') return a;
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}
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return false;
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}
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function parseRef(name: string, pos: Position | null, item: symbol): Pattern {
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const s = item.description;
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if (s === void 0) invalidPattern(name, item, pos);
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if (s[0] === '=') return Record(M.$lit, [Symbol.for(s.slice(1))]);
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const pieces = s.split('.');
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if (pieces.length === 1) {
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return recordPosition(Record(M.$ref, [M.$thisModule, item]), pos);
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} else {
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return recordPosition(Record(M.$ref, [
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pieces.slice(0, pieces.length - 1).map(Symbol.for),
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Symbol.for(pieces[pieces.length - 1])
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]), pos);
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}
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}
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function parseBase(name: symbol, body: Array<Input>): Pattern {
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body = peel(body) as Array<Input>;
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if (body.length !== 1) {
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invalidPattern(stringify(name), body, body.length > 0 ? position(body[0]) : position(body));
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}
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const pos = position(body[0]);
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const item = peel(body[0]);
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const walk = (b: Input): Pattern => parseBase(name, [b]);
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const namedwalk = (b: Input): NamedPattern => {
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const name = findName(b);
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if (name === false) return walk(b);
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return Record(M.$named, [name, walk(b)]);
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};
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const walkitems = (b: Input): Pattern[] => {
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b = peel(b);
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if (!Array.isArray(b)) complain();
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return b.map(walk);
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};
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function complain(): never {
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invalidPattern(stringify(name), item, pos);
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}
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if (typeof item === 'symbol') {
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return parseRef(stringify(name), position(body[0]), item);
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} else if (Record.isRecord<Input, Tuple<Input>, never>(item)) {
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const label = item.label;
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if (Record.isRecord<Input, [], never>(label)) {
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if (label.length !== 0) complain();
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switch (label.label) {
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case M.$lit:
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if (item.length !== 1) complain();
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return Record(M.$lit, [item[0]]);
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case M.$or:
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if (item.length !== 1) complain();
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return Record(M.$or, [walkitems(item[0])]);
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case M.$and:
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if (item.length !== 1) complain();
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return Record(M.$and, [walkitems(item[0])]);
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case M.$rec:
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if (item.length !== 2) complain();
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return Record(M.$rec, [walk(item[0]), walk(item[1])]);
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default:
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complain();
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}
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} else {
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return Record(M.$rec, [Record(M.$lit, [label]), Record(M.$tuple, [item.map(namedwalk)])]);
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}
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} else if (Array.isArray(item)) {
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if (is(item[item.length - 1], M.DOTDOTDOT)) {
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if (item.length < 2) complain();
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return Record(M.$tuple_STAR_, [
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item.slice(0, item.length - 2).map(namedwalk),
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namedwalk(item[item.length - 2]),
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]);
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} else {
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return Record(M.$tuple, [item.map(namedwalk)]);
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}
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} else if (Dictionary.isDictionary<Input, never>(item)) {
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if (item.size === 2 && item.has(M.DOTDOTDOT)) {
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const v = item.clone();
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v.delete(M.DOTDOTDOT);
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const [[kp, vp]] = v.entries();
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return Record(M.$dictof, [walk(kp), walk(vp)]);
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} else {
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return Record(M.$dict, [item.mapEntries<Pattern, Input, never>(([k, vp]) =>
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[strip(k), walk(vp)])]);
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}
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} else if (Set.isSet<never>(item)) {
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if (item.size !== 1) complain();
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const [vp] = item.entries();
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return Record(M.$setof, [walk(vp)]);
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} else {
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return Record(M.$lit, [strip(item)]);
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}
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}
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