HFL Hash Functions:

• Below is a list of hash-manipulation functions built into HFL.
• NOTE: These are normal functions, not object methods.
• hash ([<init-value-pairs>])

  where:

  <init-value-pairs>

  :=

  <value-pair> [, <value-pair>]*

  <value-pair>

  :=

  <key>, <expresion>
  • Creates a new hash table.
  • Once created, hash entries are accessed using the same syntax as javascript object field values.
  • NOTE: The data structure created by 'hash()' is a true hash table, as opposed to being implemented as a javascript object.
    • The difference is that a true hash table only contains the hash entries, without all of the rest of the object overhead.
    • In particular, this means that the foreach() operator will only find the hash entries, not all of the other properties and method entries that are associated with true javascript-compatible objects.
  • If the initialization value pairs are specified, the hash table is pre-populated with their values. Each entry is specified as a pair, with each odd value being a hash key and each even value being the previous key's value. The value can be any valid expression.
  • EXAMPLE

  • var myhash = hash('dog', 'Spot', 'cat', 'Fluffy', 'num', 1 + 2);
    
    // Prints "My dog's name is Spot"
    print("My dog's name is "+myhash['dog']);
    
    // Add new entry to hash table
    myhash['bird'] = 'Tweety';
    

• printHash ([<file-handle>,] <label>, <hash-table> [, <quote>]*)

  where:

  <label>

  :=

  Text string to be displayed as a banner

  <quote>

  :=

  Character to be used as a quote around elements
  • Prints the contents of a hash table, with the <label> above the list as a banner header, either to the console, or written to a file.
  • To write to a file, a file must first be opened for 'write' or 'append' access using the openFile() function. Then its file handle is passed to 'printHash' as the optional <file-handle> argument.
  • If the optional <file-handle> is not specified, prints to the console.
  • EXAMPLE

  • var $h = hash('a', 1, 'b', 2, 'c', 3);
    printHash("HASH TABLE CONTENTS", $h);
    

    • RESULTS:

    • HASH TABLE CONTENTS
      -----------
      a => 1
      b => 2
      c => 3
      -----------