src/core/Line.ts

   1 // Copyright 2020 Blue Static <https://www.bluestatic.org>
   2 // This program is free software licensed under the GNU General Public License,
   3 // version 3.0. The full text of the license can be found in LICENSE.txt.
   4 // SPDX-License-Identifier: GPL-3.0-only
   5
   6 import TaxReturn from './TaxReturn';
   7 import * as Trace from './Trace';
   8 import Form, { FormClass } from './Form';
   9
  10 export abstract class Line<T> {
  11   private _description?: string;
  12
  13   _id: string;  // _id is set by Form.init().
  14   form: Form<any, any>;  // Set by Form.init();
  15
  16   constructor(description?: string) {
  17     this._description = description;
  18   }
  19
  20   get id(): string {
  21     return this._id;
  22   }
  23
  24   get description(): string {
  25     return this._description;
  26   }
  27
  28   abstract value(tr: TaxReturn): T;
  29 };
  30
  31 type ComputeFunc<T> = (tr: TaxReturn) => T;
  32
  33 export class ComputedLine<T> extends Line<T> {
  34   private _compute: ComputeFunc<T>;
  35
  36   constructor(compute: ComputeFunc<T>, description?: string) {
  37     super(description);
  38     this._compute = compute;
  39   }
  40
  41   value(tr: TaxReturn): T {
  42     Trace.begin(this);
  43     const value = this._compute(tr);
  44     Trace.end();
  45     return value;
  46   }
  47 };
  48
  49 export class ReferenceLine<F extends Form<any>,
  50                            L extends keyof F['lines'],
  51                            T extends ReturnType<F['lines'][L]['value']>>
  52                                extends Line<T> {
  53   private _form: FormClass<F>;
  54   private _line: L;
  55   private _fallback?: T;
  56
  57   // If creating a ReferenceLine and F is the same class as the
  58   // the one the Line is in, erase |form|'s type with |as any| to
  59   // keep TypeScript happy.
  60   constructor(form: FormClass<F>, line: L, description?: string, fallback?: T) {
  61     super(description || `Reference ${form.name}@${line}`);
  62     this._form = form;
  63     this._line = line;
  64     this._fallback = fallback;
  65   }
  66
  67   value(tr: TaxReturn): T {
  68     Trace.begin(this);
  69     const form: F = tr.findForm(this._form);
  70     if (this._fallback !== undefined && !form) {
  71       Trace.end();
  72       return this._fallback;
  73     }
  74     const value: T = form.getValue(tr, this._line);
  75     Trace.end();
  76     return value;
  77   }
  78 };
  79
  80 export class InputLine<U = unknown, T extends keyof U = any> extends Line<U[T]> {
  81   private _input: T;
  82   private _fallback: U[T];
  83
  84   form: Form<any, U>;
  85
  86   constructor(input: T, description?: string, fallback?: U[T]) {
  87     super(description || `Input from ${input}`);
  88     this._input = input;
  89     this._fallback = fallback;
  90   }
  91
  92   value(tr: TaxReturn): U[T] {
  93     Trace.begin(this);
  94     if (!this.form.hasInput(this._input) && this._fallback !== undefined) {
  95       Trace.end();
  96       return this._fallback;
  97     }
  98     const value = this.form.getInput<T>(this._input);
  99     Trace.end();
 100     return value;
 101   }
 102 };
 103
 104 export class AccumulatorLine<F extends Form<any>,
 105                              L extends keyof F['lines']>
 106                                  extends Line<number> {
 107   private _form: FormClass<F>;
 108   private _line: L;
 109
 110   constructor(form: FormClass<F>, line: L, description?: string) {
 111     super(description || `Accumulator ${form.name}@${line}`);
 112     this._form = form;
 113     this._line = line;
 114   }
 115
 116   value(tr): number {
 117     Trace.begin(this);
 118     const forms: F[] = tr.findForms(this._form);
 119     const value = sumLineOfForms(tr, forms, this._line);
 120     Trace.end();
 121     return value;
 122   }
 123 };
 124
 125 export class UnsupportedLine extends Line<number> {
 126   constructor(description?: string) {
 127     super(description || 'Unsupported');
 128   }
 129
 130   value(tr): number {
 131     // Unsupported lines are deliberately omitted from Trace.
 132     return 0;
 133   }
 134 };
 135
 136 export function sumLineOfForms<F extends Form<any>, L extends keyof F['lines']>(
 137     tr: TaxReturn, forms: F[], line: L): number {
 138   const reducer = (acc: number, curr: F) => acc + curr.getValue(tr, line);
 139   return forms.reduce(reducer, 0);
 140 }
 141
 142 export function sumFormLines<F extends Form<any>, L extends keyof F['lines']>(
 143     tr: TaxReturn, form: F, lines: L[]): number {
 144   let value = 0;
 145   for (const line of lines)
 146     value += form.getValue(tr, line);
 147   return value;
 148 }