Eliminating of some ambiguous conditions

[ruv]

A list of ambiguous conditions that are considered as candidates to convert them into an unambiguous exceptions with assigned throw codes (see also #1) should be developed.

Note: the corresponding new test cases should be also added, if possible.

The list of ambiguous condition is provided in the section 4.1.2 Ambiguous conditions.

The list below is under construction, it will be updated right here.

Mandatory

• specify behavior for 17.6.1.0245 /STRING when n > u1 (an implicit ambiguous condition exists at the moment); options: throw an exception, or make u2 zero.
• a name is not found and not a number (todo: a lexeme it not recognized)
  • throw code -13
  • it should be embedded into 3.4.2 Finding definition names, to don't repeat in every glossary entry
• a definition name too long (6.1.0450 :, 15.6.2.2264 SYNONYM, and other defining words)
• an empty lexeme is encountered unexpectedly (6.1.0895 CHAR, 6.1.2033 POSTPONE, 11.6.2.1714 INCLUDE, and other parsing words)
  • see also a discussion about char — the word char shall not return a random character or a delimiter.
• the search order is empty in 16.6.2.0715 ALSO, 16.6.2.2037 PREVIOUS, 16.6.1.1180 DEFINITIONS, 16.6.2.1590 FORTH.
• an I/O exception occurs reading the file, or an I/O exception occurs while closing the file (11.6.1.1718 INCLUDED, 11.6.1.1717 INCLUDE-FILE).
• a named file can not be opened (11.6.1.1718 INCLUDED).
  • distinguish non-existent file (ior code -38) and access denied (a new ior should be introduced)
• A deferred word is not set with an execution token
  • a new ior should be introduced

Feasible

• the search order is overflow in 16.6.2.0715 ALSO, 16.6.1.2197 SET-ORDER.
• a new word list cannot be created by 16.6.1.2460 WORDLIST.
• insufficient space in the dictionary
• "if u (block number) is zero" (7.6.1.1790 LOAD).
• "if u is not an available block number" (7.6.1.0820 BUFFER, 7.6.1.0800 BLOCK, 7.6.2.1770 LIST, 7.6.1.1790 LOAD).

Optional

• "if deallocated memory contains definitions" (3.3.3.2 Contiguous regions, 6.1.0710 ALLOT)

Difficult to implement

• "if definitions or data required for correct execution of the program are removed during execution of name"
  (6.2.1850 MARKER, 15.6.2.1580 FORGET)