Context language and compiler for Windows basically corresponds to versions 1.1 for DOS, but some changes are present. Of course, absence of fully compatibility with the preceding version is not good, but all changes are made to correct defects of DOS version.

Direct translation of DOS-versions 1.3 (the most full version of Context language) to Windows is possible and was partly made, but this translation keep all defects of DOS-version and make compiler source more complex. Context 2.0 - a new compiler, but it uses some ideas, realized in DOS versions. Integrated syntax and semantic analyzer are similar to used in DOS versions 1.0-1.3, but code generator is completely separated from it. Analyzer produces syntax trees for all functions of program. It requires more RAM, but today it is unessential.

Version with number 2.01 works in DOS and can be used for performing the first compilation of Windows versions (2.02-2.12), but in real partly translated version 1.3 was used.

Changes and additions in language

• Using of one name for different global objects are prohibited, for example, const and global variable can't have same name. Also keywords can't be used as object names.
• Empty blocks are prohibited, if empty block are necessary, it must contain null operator. This improve program readability.
• To organize infinite loop construction do ... end must be used instead of while TRUE do ... end.
• Short circuit boolean evaluation. For example see expression F()=0 | G()=0. If function F() return zero, function G() not called.
• Nongraphic characters in strings and character constants. Presentations of nongraphic characters consists of tilde (~) and graphic character. In current version next characters may be used:
  • ~t - horizontal tabulation
  • ~r - caret return
  • ~n - new line
  • ~0 - zero
  • ~C - any other character C, for example, ~~ - tilde
• Explicit type conversions. Construction [@]Type(Expression) are used. In current version only conversions of char to byte, word and int are implemented.
• Constant expressions may be used as constants
• Simple global variables may be initialized
• Second assignment operator (:=). It added because using of one symbol as assignment and comparison is not good
• File inclusion facility with include "File_name" directive. include may appears only at global definitions level, each file are included in program only once. For example, if file A are included into file B, and files A and B are included into program, only one copy of file A appears in program. Unreferenced code and data are eliminated by compiler.

Windows specific

• Synonyms. For each object in program second name nay be defined, for example synonym DWORD word
• External functions. Each function from external DLL must be declared as external DLL_name[.Function_name];

Limitations

• There are no function types, reference to function are assumed as reference to void
• Only direct recursion allowed
• There are no build-in assembler
• Code generator are relatively primitive

All this limitations are made to simplification of compiler. Future directions:

• Base type real
• Enumerations
• Function types and function references
• Classes
• Optimizer

To produce executable files assembler FASM (www.flatassembler.net) are used. Compiler was tested with FASM 1.49. Previous versions uses Borland TASM32 and TLINK32. The main reason of this change is using of freeware product.