Data model for tables and schema

.vscode/settings.json

+{
+    "typescript.tsdk": "node_modules\\typescript\\lib"
+}
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src/data/data.ts

+/*
+ * Copyright (c) 2017 molio contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author David Sehnal <david.sehnal@gmail.com>
+ */
+
+export interface File {
+    readonly name?: string,
+    readonly blocks: ReadonlyArray<Block>
+}
+
+export interface Block {
+    readonly header?: string,
+    readonly categories: { readonly [name: string]: Category }
+}
+
+export interface Category {
+    readonly rowCount: number,
+    getField(name: string): Field | undefined
+}
+
+export namespace Category {
+    export const Empty: Category = { rowCount: 0, getField(name: string) { return void 0; } };
+}
+
+export const enum ValuePresence {
+    Present = 0,
+    NotSpecified = 1,
+    Unknown = 2
+}
+
+export const enum ArrayKind {
+    String,
+    Float32,
+    Float64
+}
+
+export type FieldArray = number[] | Float32Array | Float64Array | Int8Array | Int16Array | Int32Array | Uint8Array | Uint16Array | Uint32Array
+
+/**
+ * Implementation note:
+ * Always implement this as a "plain" object so that the functions are "closures"
+ * by default. This is to ensure that the schema access works without definiting
+ * additional closures.
+ */
+export interface Field {
+    readonly isDefined: boolean,
+
+    str(row: number): string | null,
+    int(row: number): number,
+    float(row: number): number,
+    bin(row: number): Uint8Array | null,
+
+    presence(row: number): ValuePresence,
+
+    areValuesEqual(rowA: number, rowB: number): boolean,
+    stringEquals(row: number, value: string | null): boolean,
+
+    toStringArray(startRow: number, endRowExclusive: number, ctor: (size: number) => FieldArray): ReadonlyArray<string>,
+    toNumberArray(startRow: number, endRowExclusive: number, ctor: (size: number) => FieldArray): ReadonlyArray<number>
+}
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src/data/schema.ts

+/*
+ * Copyright (c) 2017 molio contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author David Sehnal <david.sehnal@gmail.com>
+ */
+
+import * as Data from './data'
+
+/**
+ * A schema defines the shape of categories and fields.
+ *
+ * @example:
+ * const atom_site = {
+ *   '@alias': '_atom_site',
+ *   label_atom_id: Field.str(),
+ *   Cartn_x: Field.float(),
+ *   Cartn_y: Field.float(),
+ *   Cartn_z: Field.float(),
+ * }
+ *
+ * const mmCIF = { atom_site };
+ */
+export type BlockDefinition = { [category: string]: CategoryDefinition }
+export type CategoryDefinition = { '@alias'?: string } & { [field: string]: Field.Schema<any> }
+
+export type Schema<Definition extends BlockDefinition> = Block<{ [C in keyof Definition]: Category<{ [F in keyof Definition[C]]: Field<Definition[C][F]['type']> }> }>
+
+export function apply<T extends BlockDefinition>(schema: T, block: Data.Block): Schema<T> {
+    return createBlock(schema, block) as Schema<T>;
+}
+
+export type Block<Categories> = Categories & {
+    readonly _header?: string,
+    /** For accessing 'non-standard' categories */
+    _getCategory(name: string): Data.Category | undefined
+}
+
+export type Category<Fields> = Fields & {
+    readonly _rowCount: number,
+    /** For accessing 'non-standard' fields */
+    _getField(name: string): Data.Field | undefined
+}
+
+export interface Field<T> {
+    readonly isDefined: boolean,
+    value(row: number): T,
+    presence(row: number): Data.ValuePresence,
+    areValuesEqual(rowA: number, rowB: number): boolean,
+    stringEquals(row: number, value: string | null): boolean,
+    /** Converts the selected row range to an array. ctor might or might not be called depedning on the source data format. */
+    toArray(startRow: number, endRowExclusive: number, ctor: (size: number) => Data.FieldArray): ReadonlyArray<T> | undefined
+}
+
+export namespace Field {
+    function create<T>(field: Data.Field, value: (row: number) => T, toArray: Field<T>['toArray']): Field<T> {
+        return { isDefined: field.isDefined, value, presence: field.presence, areValuesEqual: field.areValuesEqual, stringEquals: field.stringEquals, toArray };
+    }
+
+    function Str(field: Data.Field) { return create(field, field.str, field.toStringArray); }
+    function Int(field: Data.Field) { return create(field, field.int, field.toNumberArray); }
+    function Float(field: Data.Field) { return create(field, field.float, field.toNumberArray); }
+    function Bin(field: Data.Field) { return create(field, field.bin, (s, e, ctor) => void 0); }
+
+    const DefaultUndefined: Data.Field = {
+        isDefined: false,
+        str: row => null,
+        int: row => 0,
+        float: row => 0,
+        bin: row => null,
+
+        presence: row => Data.ValuePresence.NotSpecified,
+        areValuesEqual: (rowA, rowB) => true,
+        stringEquals: (row, value) => value === null,
+
+        toStringArray: (startRow, endRowExclusive, ctor) => {
+            const count = endRowExclusive - startRow;
+            const ret = ctor(count) as any;
+            for (let i = 0; i < count; i++) { ret[i] = null; }
+            return ret;
+        },
+        toNumberArray: (startRow, endRowExclusive, ctor) => new Uint8Array(endRowExclusive - startRow) as any
+    };
+
+    export interface Schema<T> { type: T, ctor: (field: Data.Field) => Field<T>, undefinedField: Data.Field, alias?: string };
+    export interface Spec { undefinedField?: Data.Field, alias?: string }
+
+    function createSchema<T>(spec: Spec | undefined, ctor: (field: Data.Field) => Field<T>): Schema<T> {
+        return { type: 0 as any, ctor, undefinedField: (spec && spec.undefinedField) || DefaultUndefined, alias: spec && spec.alias };
+    }
+
+    export function str(spec?: Spec) { return createSchema(spec, Str); }
+    export function int(spec?: Spec) { return createSchema(spec, Int); }
+    export function float(spec?: Spec) { return createSchema(spec, Float); }
+    export function bin(spec?: Spec) { return createSchema(spec, Bin); }
+}
+
+class _Block implements Block<any> { // tslint:disable-line:class-name
+    header = this._block.header;
+    getCategory(name: string) { return this._block.categories[name]; }
+    constructor(private _block: Data.Block, schema: BlockDefinition) {
+        for (const k of Object.keys(schema)) {
+            Object.defineProperty(this, k, { value: createCategory(k, schema[k], _block), enumerable: true, writable: false, configurable: false });
+        }
+    }
+}
+
+class _Category implements Category<any> { // tslint:disable-line:class-name
+    _rowCount = this._category.rowCount;
+    _getField(name: string) { return this._category.getField(name); }
+    constructor(private _category: Data.Category, schema: CategoryDefinition) {
+        const fieldKeys = Object.keys(schema).filter(k => k !== '@alias');
+        const cache = Object.create(null);
+        for (const k of fieldKeys) {
+            const s = schema[k];
+            Object.defineProperty(this, k, {
+                get: function() {
+                    if (cache[k]) return cache[k];
+                    const field = _category.getField(s.alias || k) || s.undefinedField;
+                    cache[k] = s.ctor(field);
+                    return cache[k];
+                },
+                enumerable: true,
+                configurable: false
+            });
+        }
+    }
+}
+
+function createBlock(schema: BlockDefinition, block: Data.Block): any {
+    return new _Block(block, schema);
+}
+
+function createCategory(key: string, schema: CategoryDefinition, block: Data.Block) {
+    const cat = block.categories[schema['@alias'] || key] || Data.Category.Empty;
+    return new _Category(cat, schema);
+}
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src/data/spec/schema.spec.ts

+/*
+ * Copyright (c) 2017 molio contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author David Sehnal <david.sehnal@gmail.com>
+ */
+
+import * as Data from '../data'
+import * as Schema from '../schema'
+
+function Field(values: any[]): Data.Field {
+    return {
+        isDefined: true,
+        str: row => '' + values[row],
+        int: row => +values[row] || 0,
+        float: row => +values[row] || 0,
+        bin: row => null,
+
+        presence: row => Data.ValuePresence.Present,
+        areValuesEqual: (rowA, rowB) => values[rowA] === values[rowB],
+        stringEquals: (row, value) => '' + values[row] === value,
+
+        toStringArray: (startRow, endRowExclusive, ctor) => {
+            const count = endRowExclusive - startRow;
+            const ret = ctor(count) as any;
+            for (let i = 0; i < count; i++) { ret[i] = values[startRow + i]; }
+            return ret;
+        },
+        toNumberArray: (startRow, endRowExclusive, ctor) => {
+            const count = endRowExclusive - startRow;
+            const ret = ctor(count) as any;
+            for (let i = 0; i < count; i++) { ret[i] = +values[startRow + i]; }
+            return ret;
+        }
+    }
+}
+
+class Category implements Data.Category {
+    getField(name: string) { return this.fields[name]; }
+    constructor(public rowCount: number, private fields: any) { }
+}
+
+class Block implements Data.Block {
+    constructor(public categories: { readonly [name: string]: Data.Category }, public header?: string) { }
+}
+
+const testBlock = new Block({
+    'atoms': new Category(2, {
+        x: Field([1, 2]),
+        name: Field(['C', 'O'])
+    })
+});
+
+namespace TestSchema {
+    export const atoms = { x: Schema.Field.float(), name: Schema.Field.str() }
+    export const schema = { atoms }
+}
+
+describe('schema', () => {
+    const data = Schema.apply(TestSchema.schema, testBlock);
+    it('property access', () => {
+        const { x, name } = data.atoms;
+        expect(x.value(0)).toBe(1);
+        expect(name.value(1)).toBe('O');
+    });
+
+    it('toArray', () => {
+        const ret = data.atoms.x.toArray(0, 2, (s) => new Int32Array(s))!;
+        expect(ret.length).toBe(2);
+        expect(ret[0]).toBe(1);
+        expect(ret[1]).toBe(2);
+    })
+});
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