@glimmer/interfaces/lib/compile/encoder.ts

import type { CompileTimeComponent } from '../../index.js';
import type { Nullable } from '../core.js';
import type { CompileTimeConstants } from '../program.js';
import type { HandleResult, NamedBlocks } from '../template.js';
import type { VmMachineOp as MachineOp, VmOp as Op } from '../vm-opcodes.js';
import type { SingleBuilderOperand } from './operands.js';
import type * as WireFormat from './wire-format/api.js';

// These values are used in the same space as standard opcodes, so we need to
// start them at a higher value to prevent collisions
export type HighLevelLabel = 1000;
export type HighLevelStartLabels = 1001;
export type HighLevelStopLabels = 1002;
export type HighLevelStart = HighLevelLabel;
export type HighLevelEnd = HighLevelStopLabels;

export type HighLevelBuilderOpcode = HighLevelLabel | HighLevelStartLabels | HighLevelStopLabels;

export type HighLevelResolveModifier = 1003;
export type HighLevelResolveComponent = 1004;
export type HighLevelResolveHelper = 1005;
export type HighLevelResolveComponentOrHelper = 1007;
export type HighLevelResolveOptionalComponentOrHelper = 1008;
export type HighLevelResolveLocal = 1010;
export type HighLevelResolveTemplateLocal = 1011;
export type HighLevelResolveStart = HighLevelResolveModifier;
export type HighLevelRevolveEnd = HighLevelResolveTemplateLocal;

export type HighLevelResolutionOpcode =
  | HighLevelResolveModifier
  | HighLevelResolveComponent
  | HighLevelResolveHelper
  | HighLevelResolveComponentOrHelper
  | HighLevelResolveOptionalComponentOrHelper
  | HighLevelResolveLocal
  | HighLevelResolveTemplateLocal;

export interface SimpleArgsOptions {
  positional: Nullable<WireFormat.Core.Params>;
  named: Nullable<WireFormat.Core.Hash>;
  atNames: boolean;
}

export interface ArgsOptions extends SimpleArgsOptions {
  named: WireFormat.Core.Hash;
  blocks: NamedBlocks;
}

export type StartLabelsOp = [op: HighLevelStartLabels];

export type StopLabelsOp = [op: HighLevelStopLabels];

export type LabelOp = [op: HighLevelLabel, op1: string];

export type HighLevelBuilderOp = StartLabelsOp | StopLabelsOp | LabelOp;

export type ResolveModifierOp = [
  op: HighLevelResolveModifier,
  op1: WireFormat.Expressions.Expression,
  op2: (handle: number) => void,
];

export type ResolveComponentOp = [
  op: HighLevelResolveComponent,
  op1: WireFormat.Expressions.Expression,
  op2: (component: CompileTimeComponent) => void,
];

export type ResolveComponentOrHelperOp = [
  op: HighLevelResolveComponentOrHelper,
  op1: WireFormat.Expressions.Expression,
  op2: {
    ifComponent: (component: CompileTimeComponent) => void;
    ifHelper: (handle: number) => void;
  },
];

export type ResolveHelperOp = [
  op: HighLevelResolveHelper,
  op1: WireFormat.Expressions.Expression,
  op2: (handle: number) => void,
];

export type ResolveOptionalComponentOrHelperOp = [
  op: HighLevelResolveOptionalComponentOrHelper,
  op1: WireFormat.Expressions.Expression,
  op2: {
    ifComponent: (component: CompileTimeComponent) => void;
    ifHelper: (handle: number) => void;
    ifValue: (handle: number) => void;
  },
];

export type ResolveTemplateLocalOp = [
  op: HighLevelResolveTemplateLocal,
  op1: number,
  op2: (handle: number) => void,
];

export type ResolveLocalOp = [
  op: HighLevelResolveLocal,
  op1: number,
  op2: (name: string, moduleName: string) => void,
];

export type HighLevelResolutionOp =
  | ResolveModifierOp
  | ResolveComponentOp
  | ResolveComponentOrHelperOp
  | ResolveHelperOp
  | ResolveOptionalComponentOrHelperOp
  | ResolveTemplateLocalOp
  | ResolveLocalOp;

export type HighLevelOp = HighLevelBuilderOp | HighLevelResolutionOp;

export type BuilderOpcode = Op | MachineOp;

export type BuilderOp = [
  op: BuilderOpcode,
  op1?: SingleBuilderOperand,
  op1?: SingleBuilderOperand,
  op1?: SingleBuilderOperand,
];

export interface EncoderError {
  problem: string;
  span: {
    start: number;
    end: number;
  };
}

/**
 * The Encoder receives a stream of opcodes from the syntax compiler and turns
 * them into a binary program.
 */
export interface Encoder {
  /**
   * Finalize the current compilation unit, add a `(Return)`, and push the opcodes from
   * the buffer into the program. At this point, some of the opcodes might still be
   * placeholders, such as in the case of recursively compiled templates.
   *
   * @param compiler
   * @param size
   */
  commit(size: number): HandleResult;

  /**
   * Push a syscall into the program with up to three optional
   * operands.
   *
   * @param opcode
   * @param args up to three operands, formatted as
   *   { type: "type", value: value }
   */
  push(
    constants: CompileTimeConstants,
    opcode: BuilderOpcode,
    ...args: SingleBuilderOperand[]
  ): void;

  /**
   * Start a new labels block. A labels block is a scope for labels that
   * can be referred to before they are declared. For example, when compiling
   * an `if`, the `JumpUnless` opcode occurs before the target label. To
   * accommodate this use-case ergonomically, the `Encoder` allows a syntax
   * to create a labels block and then refer to labels that have not yet
   * been declared. Once the block is complete, a second pass replaces the
   * label names with offsets.
   *
   * The pattern is:
   *
   * ```ts
   * encoder.reserve(Op.JumpUnless);
   * encoder.target(encoder.pos, 'ELSE');
   * ```
   *
   * The `reserve` method creates a placeholder opcode with space for a target
   * in the future, and the `target` method registers the blank operand position
   * to be replaced with an offset to `ELSE`, once it's known.
   */
  startLabels(): void;

  /**
   * Finish the current labels block and replace label names with offsets,
   * now that all of the offsets are known.
   */
  stopLabels(): void;

  /**
   * Mark the current position with a label name. This label name
   * can be used by any other opcode in this label block.
   * @param name
   * @param index
   */
  label(name: string): void;

  error(error: EncoderError): void;
}