deci.vm

deci.vm - simple proof-of-concept interpreter uses IEC61131-3 ST like-ish programming language as basis for its syntax.

Dependencies

1. C++ compiler with C++11 support
2. CMake 3.5
3. GNU Bison 3.0.4
4. Flex 2.6.4

Platform

Theoreticaly, code can be compiled and run on any platform, where one can build code using modern C++11 compiler, but Windows lacks decent Flex/GNU Bison version, so no luck there. I'll include a copy of generated code to use when no Flex/GNU Bison available in some future releases.

API

Library has several distinct parts:

• classes implementing any/variant pattern:
  • value_t - basic abstract class;
  • nothing_t - singleton class implements NULL-class patter;
  • number_t - double precision IEEE 754 number;
  • string_t - byte string;
  • array_t - sequence container, elements stored contiguously;
  • reference_t - can reference to other objects and keeps count;
  • dictionary_t - unordered associative container;
  • function_t - abstract class implements execution capabilities;
• classes implementing virtual machine (VM):
  • stack_t - implements VM execution context, which consists of defined variables and stack itself;
  • vm_t - simple wrapper, when called tries to execute function on top of its stack;
  • program_t - class implements user-defined interpretable code;
  • binop_t - template implements basic function of two arguments;
  • unrop_t - template implements basic function of single argument;
• standard library of functions to use with user-defined code:
  • sum_t - A + B;
  • sub_t - A - B ;
  • mul_t - A * B;
  • div_t - A / B;
  • ls_t - A < B;
  • gr_t - A > B;
  • le_t - A <= B;
  • ge_t - A >= B;
  • eq_t - A == B;
  • neq_t - A != B;
  • or_t - A || B;
  • and_t - A && B;
  • xor_t - A ^ B;
  • pow_t - pow(A, B);
  • mod_t - A%B;
  • not_t - !A;
  • neg_t - -A;
  • print_t - print to stdout;
• ST language compiler
  • deci_scanner_t - lexer class, body of get_next_token function generated by Flex from "iec61131.l";
  • parser_t - parser class, class declaration/definition generated by GNU BISON from "iec61131.y";
  • ast_item_t - interface class implementing single AST branch/leaf, method Generate writes compiled code for program_t to interpret;
  • ast_number_t - numeric constant leaf;
  • ast_identifier_t - some text nonterminal symbol in program;
  • ast_arg_list_t - list of arguments divied by comma;
  • ast_postfix_t - postfix operation (mainly function calls);
  • ast_binary_t - infix binary operation;
  • ast_unary_t - prefix unary operation;
  • ast_return_t - operation which dumps unassigned expression results;
  • ast_set_t - operation set new variable value;
  • ast_t - sequence of ast_item_t elements;
  • ast_if_t - if/else/end_if statement;
  • ast_for_t - for/end_for statement;
  • ast_while_t - while/end_while statement;
  • ast_repeat_t - repeat/end_repeat statement;

Test Code

1. basic_test - small obsolete code to test deci::program_t assembler
2. values_test - small unfinished code to test deci::value_t derived classes
3. compile_test - simple REPL iterpreter, or non-interactive interpreter of program given in test arguments list.

Build

mkdir stage
cd stage
cmake ../
cmake --build ./

Run Interpreter

./stage/compile_test ./test/prog.st

Run REPL

./stage/compile_test

>> 123 + 321;
444