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CHANGELOG.md

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Decision v0.3.0 - 29th February 2020

NOTE: This update changes some of the fundamental definitions of items in Decision, and thus will break most source files, and all object files, from previous Decision versions!

Compiler

Comments

  • Removed multi-line comments.
  • Added single-line comments: Anything after and including the > symbol on the same line will be ignored by the compiler.

Metadata

  • All nodes, sockets, variables, functions and subroutines now have both names and descriptions which are accessible via the C API.
    • The Variable property now has a description argument, e.g. Variable(count, Integer, 0, "Counts how many pies you've eaten today.")
    • The Function and Subroutine properties now have a description argument, e.g. Function(Double, "Doubles the number.")
    • The FunctionInput and FunctionOutput argument specification has changed:
      • FunctionInput(functionName, inputName, inputType [,inputDefaultValue [, inputDescription]])
      • FunctionOutput(functionName, outputName, outputType [, outputDescription])

Core Functions

  • Integers as inputs to bitwise operators is now supported.
  • Booleans as inputs to Equal and NotEqual is now supported.
  • Reimplemented Length to use the C function strlen.

The VM

  • Changed the Decision VM to be stack-based, rather than register-based.
    • The VM stack can grow and shrink in size, meaning the VM is not limited in the amount of memory it can use anymore.
    • The stack holds temporary values (previously stored in the registers), arguments and return values (previously stored in the general stack), saved return addresses (previously stored in the call stack), as well as saved frame pointers.
  • Now produces a runtime error if a division by 0 is attempted.

Object Files

  • Compiled object files (.dco) now store the version of Decision that created them. The compiler now checks to see if an object file was made with a future version of Decision, and will check in future releases for incompatible versions.

The C API

  • C functions are now stored in sheets, rather than in a global list.
  • Sheets can now be loaded with an initial list of included sheets, which are loaded before any compilation happens.
  • Sheets now have an allowFree property that stops sheets that include it from freeing the sheet when they are freed.
  • Bytecode now stores the pointer to the CFunction struct containing the actual function pointer, rather than the function pointer itself, to conform to the ISO C Standard.

Debugging

  • The ability to debug Decision sheets has now been added, and can be done through the C API (see ddebug.h).
    • If compiling in debug mode, code generation will store information about instructions in the bytecode, and optimisation will no longer occur.
    • You can provide agendas to debugging sessions, which allows you to give function pointers which are called when certain events happen, and also allows you to provide node and wire breakpoints.
    • You can then run debug sessions, which essentially simulates running the Decision VM.
    • A C test has been added to test this functionality.

Refactoring

  • Split large source files into smaller ones to improve code readability.
    • The graph components of sheets (i.e. the nodes and wires) have their own set of files, dgraph.c and dgraph.h.
    • Finding the definitions of names has been moved to dname.c and dname.h.
    • Decision object files now have their own set of source files, dobj.c and dobj.h, and the code has been revamped to be less error-prone.
  • Removed d_insert_bytecode, as it is no longer used.
  • Removed all calls to "safe" Visual C++ functions, due to considerations of standardisation.

Documentation

  • The compiler now has a --export-core flag, which will output the core reference in JSON format.
    • This is used in conjunction with an extension added to the user manual, which reads the JSON and displays the core reference automatically.
  • Both the user and developer manuals have been updated for changes made in this update.

Optimisations

  • Changed the build system such that most of the code compiles to a singular library (which is either static or shared, static by default, see README.md for more details), and link the executable to that library. This has reduced the compile time significantly.
    • Compiler warnings have also been set to maximum on both the executable and the library that is built.
  • Syntax Analysis has been optimised to check the next token ahead before dedicating itself to a syntax definition.
  • Nodes now reference their definitions, which reduces data redundancy.
  • Wires are stored in an ordered list, rather than as direct pointers, to reduce the number of memory allocations and to remove the potential for dangling pointers.

Bug Fixes

  • Fixed a bug where reduced types were no longer compatible with their connected sockets, but the compiler didn't throw an error.
  • Fixed a bug where a stack overflow would occur if there was a circular include cycle in the sheets.
  • Fixed a bug where the compiler would let subroutines with return values and without ending return nodes compile, leading to undefined values being returned.

Decision v0.2.0 - 16th January 2020

Strings

  • Added the Length core function, which returns the number of characters in a given string.
  • Added tests for the Length function.

Compiler

  • The compiler now automatically converts integer literals to float literals if the socket is a float-only socket.
  • Moved the linking stage to the last step in loading a string instead of the first step in running a string.
  • Optimised by adding a stage in linking dedicated to pre-calculating the memory locations of external variables and pointers.
  • Fixed a bug where compiled sheets maintained their external pointers.

The C API

  • Added d_run_function to decision.h, which allows for running Decision functions and subroutines from C.
  • Added dcfunc.c and dcfunc.h, which allow for running C functions from Decision.
  • Added new opcode OP_CALLC to the VM.
  • Added a .c section to compiled object files to store the specifications of C functions the sheet uses.
  • The compiler, as part of finding the definition of a name, will look at defined C functions in dcfunc.c to find one.
  • Added d_vm_pop_stack, d_vm_pop_stack_float and d_vm_pop_stack_ptr to dvm.h.
  • Added d_vm_push_stack, d_vm_push_stack_float and d_vm_push_stack_ptr to dvm.h.
  • Added tests for the C API to the CMake project.

Documentation

  • Added "String Manipulation" section to the user manual.
  • Added "The C API" chapter to the developer manual.
  • Added note in the user manual about semi-colons being valid end of statement symbols.

Decision v0.1.1 - 25th December 2019

  • Changed the bool definition to the one in stdbool.h, which makes it consistent to the C++ definition of the bool type.

Decision v0.1.0 - 19th December 2019

This is the first release of Decision!

Feel free to download it and give it a try - if you want to start contributing to the project, have a look at CONTRIBUTING.md, and have fun!