Zxbasic

===
+ ! Fixed a bug in constant evaluation
+ ! Allows non constant initialization of scalar variables like DIM a$ = "hi"
+ ! Fix bugs in the assembler not allowing complex expressions
+ ! Fix a rare crash when using functions before declaring them

[v1.4.0.x](https://github.com/boriel/zxbasic/tree/v1.4.0.x)
===

This is a long (near 3 year) set of versions in which the compiler
was refactored in many places. The compiler migrated from one-pass
no objects compiler to a multiple pass object like compiler.
This not only makes the code much more maintainable and elegant, but
also a bit faster.

Technical stuff:
Now the AST uses an heterogeneous AST pattern, allowing both children
traversal using indexes (and also primitives like `node.appendChild`)
and attribute traversal which depends on the `symbolTYPE` being parsed.
e.g. for `symbolBINARY` (binary expressions), we have `node.left`, `node.right`,
`node.operand`, but also `node.children[0]`, `node.children[1]`.

The major feature in this release is the posibility to declare nested functions.
These functions are declared within others, and can only be called from within
their respective parent function body.

===
+ ! Fixed a bug in `USR <string>`
+ ! Fixed a bug in `SAVE` / `LOAD`
+ ! Fixed a serious bug in the preprocessor
+ ! Fixed a bug with `DIM` and constants
+ ! Fixed a bug with `SHL`/`SHR` for 0 shifts
+ Added `-D` option. ZXBasic now allows commandline macro definition
+ ! Fixed a bug with `CODE` and `INKEY$`
+ ! Fixed a bug with string slicing assignation (e.g. `a$(3) = "x"`)
+ ! Fixed a bug with arrays of integer assignation (e.g. `a(3) = 5`, being a of Integer type)
+ ! Fixed a bug with peephole optimizer (`-O3`)
+ Some changes and code refactorization towards 2.x branch

===
+ ! Fixed a serious bug with ALL integer (signed/unsigned) operands
which were not working correctly under some circumstances.
+ ! Fixed some bugs which made the compiler to crash when a syntax error is found.
+ ! Fixed a bug in `ALIGN` (assembler)
+ ZXBasic python version is now PyPy compatible.
+ `RND` is now MUCH faster and produces better random patterns (thanks to Britlion)
+ Compiler speed is now almost 100% faster!
+ Some code optimization
+ Added a recursive pattern fill library with an example (thanks to Britlion)
+ Fixed some bugs in the preprocessor which prevented some chars to be written
+ Fixed a bug with `PRINT` and comma position
+ Fixed a bug in `PEEK` which was related to the backend
+ Fixed more than 50 other minor bugs in both the compiler and the assembler
+ `THEN` keyword is now optional in `IF` statements

===
+ Code rearranged and restructured for future deep refactorizations.
+ ! Complete rewritten backend (or almost!) to fix a bug in code
generation which was being suboptimal.<br />Now generated code is
much faster and take less memory than before!
+ Added support for Bitwise syntax (`|`, `&`, `~`)
+ Fixed some bugs in ASM
+ ! Fixed some bugs in the peephole optimized (`-O3`)
+ ! Fixed a bug with line continuation comments /' ...
+ ! Fixed bugs in ASM parser regarding to comments
+ Added `ATTRADDR()` function in `<attrib.bas>`
+ ! Many more bugs fixed related to `STRING` memory leak
+ ! Fixed a bug related to parameters.
+ Some optimizations for code size and speed for `FLOAT` types
+ Optimization for `STRING` parameters
+ Optimization for 32 bit values
+ ! Fixed a bug for `Uinteger`/`Integer` arrays assignation
+ ! Fixed 2 bugs in `CAST` operation and type conversion
+ ! Fixed a bug in `OVER` attribute during `PRINT`
+ Added PONG game example
+ ! Fixed a bug in `POKE`
+ ! `PRINT` optimized and slightly faster. Now fully compatible with
**Sinclair Basic** (no *Out of Screen* error on program exit)
+ ! `CSRLN` and `POS` optimized to this new `PRINT` scheme!
... and much much more

===
+ `DRAW` is now much faster (and a bit more larger)
+ `PLOT`, `DRAW` and `CIRCLE` now supports change screen address (for double-buffering)
+ Added `LBOUND()` and `UBOUND()` functions
+ ! Fixed a bug in `IF`/`THEN`/`ELSEIF`/`ELSE` construct (thanks to LTee)
+ Added a completely new preprocessor which now support true macros and
better line counting handling. This is a major change in the compiler.
+ Added string management library with `UCase()`, `LCase()`, `Ucase2()`, `LCase2()`, `InStr()` and `StrPos()`
+ ! UDG where not being handled into the Heap, which might lead to program
crash (fixed). This is done only if `--sinclair` or `-Z` cmdline flag is used.
+ Added support for `BIN`, so `BIN 01010101` is also accepted now.
+ ! Fixed a bug with string parameters passed by value (again) not being correctly
free upon return and crashing the program.
+ `BEEP` with constant duration and pitch (e.g. `BEEP 1, 2`) has been
optimized for space (and also slightly faster)
+ Added Flight Simulator example

===
+ Bitwise `bAND`, `bOR`, `bXOR`, `bNOT` finally added for 8, 16 and 32 bits
+ The assembler now supports `ALIGN <integer>` directive
+ Added support for logical `XOR` (`IF A XOR B THEN`...)
+ Added support for checking out of memory in runtime (`--debug-memory`)
+ Added support for checking BREAK in runtime (`--enable-break`)
+ Added support for Subscript Out of Range in runtime (`--debug-array`)
+ Added support for `--strict-boolean` (0 or 1) values
+ Added `print64()` by Britlion library routine, and Mojon Twins FourSpriter version (more to come).
+ Fixed a bug in `RANDOMIZE` which wasn't updating the seed correctly.
+ Fixed a pragma typo in `POS.bas` library which lead to errors.
+ ! Fixed a bug in `STR$`, `VAL`, `CHR$` and `CODE` which could crash the program.
+ ! Fixed a bug in string comparison
+ ! Fixed 2 more bugs in the peephole optimizer (`-O3`) which could crash the program.
+ ! Fixed some syntax bugs. `PI()` and `RND()` are now allowed.<br />
Calling functions with no parenthesis is allowed too.
+ ! Fixed a parser bug in which empty `WHILE` / `DO` .. `LOOP` loops crashed the compiler. Fixed.
+ ! Array access has been optimized for speed. Now faster.
+ ! For loops have been slightly optimized.
+ ! MEM_FREE heap routine has been slightly optimized.
+ The `print*` intermediate code instructions have been removed and converted to routines.
+ Lot of code refactoring, and moved to the standard trunk/tag/branches SVN repository scheme.
+ String expressions are now standardized (like any other data type).
+ TDD: Begin to create tests cases for the compiler.