apg-unicode/src/identifiers.js

JavaScript APG parser of Unicode code point arrays

// ## Identifiers Reference Guide

// This file defines a comprehensive set of numerical identifiers used
// throughout the parsing and translation process.
// Each identifier is designed for memory-efficient representation and fast lookup,
// ensuring robust performance of the parser and the application's callback functions.
// These constants serve as identifiers for:

// - **Parse Tree Node Operators**
//   Representing parse tree node types in the grammar object and in the parser during parsing.

// - **Parser States**
//   Identifies parser states during depth-first traversal of the parse tree.

// - **Abstract Syntax Tree (AST) Traversal Flags**
//   Identifies directional flow during the depth-first traversal of the AST.

// - **Input String Array Types**
//   Allows quick differentiation between the allowed input string array types.

export { identifiers };
const identifiers = {
  // These identify the operator types in the grammar object as well as the parser.
  // **Note:** These must match the values in [apg-js 4.4.0](https://github.com/ldthomas/apg-js) generator.

  /* the original seven ABNF operators */
  ALT: 1 /* alternation */,
  CAT: 2 /* concatenation */,
  REP: 3 /* repetition */,
  RNM: 4 /* rule name */,
  TRG: 5 /* terminal range */,
  TBS: 6 /* terminal binary string, case sensitive */,
  TLS: 7 /* terminal literal string, case insensitive */,

  /* the super set, SABNF operators */
  UDT: 11 /* user-defined terminal */,
  AND: 12 /* positive look ahead */,
  NOT: 13 /* negative look ahead */,

  // Used by the parser and the user's `RNM` and `UDT` callback functions.
  // Identifies the parser state as it traverses the parse tree nodes.
  // - **ACTIVE** - indicates the downward direction through the parse tree node.
  // - **MATCH** - indicates a successfully matched phrase, of length \> 0
  // - **EMPTY** - indicates a successfully matched empty phrase, length = 0
  // - **NOMATCH** - indicates failure to match any phrase at all
  ACTIVE: 100,
  MATCH: 101,
  EMPTY: 102,
  NOMATCH: 103,

  // Used by `AST` translator and the application's callback functions
  // to identify the node visitation states during the depth-first traversal.
  // - **SEM_PRE** - indicates the downward (pre-branch) direction through the `AST` node.
  // - **SEM_POST** - indicates the upward (post-branch) direction through the `AST` node.
  SEM_PRE: 200,
  SEM_POST: 201,
  SEM_OK: 300 /* ignored - retained for backwards compatibility */,

  // The input string array type identifiers.
  // - **UINT8** - Uint8Array
  // - **UINT16** - Uint16Array
  // - **UINT32** - Uint32Array
  // - **ARRAY** - Array
  UINT8: 400,
  UINT16: 401,
  UINT32: 402,
  ARRAY: 403,

  // `idName` translates a numerical identifier into a human-readable name.
  //  * @param {number} s - an identifier from the list above
  //  * @returns {string} - the ASCII name of the identifier
  idName: (s) => {
    switch (s) {
      case identifiers.ALT:
        return 'ALT';
      case identifiers.CAT:
        return 'CAT';
      case identifiers.REP:
        return 'REP';
      case identifiers.RNM:
        return 'RNM';
      case identifiers.TRG:
        return 'TRG';
      case identifiers.TBS:
        return 'TBS';
      case identifiers.TLS:
        return 'TLS';
      case identifiers.UDT:
        return 'UDT';
      case identifiers.AND:
        return 'AND';
      case identifiers.NOT:
        return 'NOT';
      case identifiers.ACTIVE:
        return 'ACTIVE';
      case identifiers.EMPTY:
        return 'EMPTY';
      case identifiers.MATCH:
        return 'MATCH';
      case identifiers.NOMATCH:
        return 'NOMATCH';
      case identifiers.SEM_PRE:
        return 'SEM_PRE';
      case identifiers.SEM_POST:
        return 'SEM_POST';
      case identifiers.SEM_OK:
        return 'SEM_OK';
      case identifiers.UINT8:
        return 'UINT8';
      case identifiers.UINT16:
        return 'UINT16';
      case identifiers.UINT32:
        return 'UINT32';
      case identifiers.ARRAY:
        return 'ARRAY';
      default:
        return 'UNRECOGNIZED IDENTIFIER';
    }
  },
};