move to a direct byte code compiler (#8)

* chore: refactor to keep only the new parser and bytecode vm

* scanner: remove Token.value field

* scanner: remove scanner.kind field

* chore: move language specification in lang package

This avoid a cyclic dependency in scanner_test which can now use
the golang/GoSpec language specification for Go.

* clean code

* scanner: export scanner fields

Also parser now generate function calls, including externals.

* chore: fix lint issues

* parser: handle strings

* wip

* parser: implement support for 'if, else, else if' statements

Resolving labels in the compiler still in progress.

* parser: support if statements, improve compiler

* improve handling of functions

* improve support of local variables

* scanner: trim leading and trailing spaces

* fixes to make fibonacci work

* parser: improve README, fix function parameters parsing

1 files changed, 110 insertions, 0 deletions

diff --git a/lang/token.go b/lang/token.go
new file mode 100644
index 0000000..3a980a4
--- /dev/null
+++ b/lang/token.go
@@ -0,0 +1,110 @@
+package lang
+
+type TokenId int
+
+const (
+	Illegal = iota
+	Comment
+	Ident
+	Int
+	Float
+	Imag
+	Char
+	String
+
+	// Operators
+	Add
+	Sub
+	Mul
+	Quo
+	Rem
+	And
+	Or
+	Xor
+	Shl    // <<
+	Shr    // >>
+	AndNot //
+
+	AddAssign
+	SubAssign
+	MulAssign
+	QuoAssign
+	RemAssign
+	AndAssign
+	OrAssign
+	XorAssign
+	ShlAssign
+	ShrAssign
+	AndNotAssign
+
+	Land
+	Lor
+	Arrow
+	Inc
+	Dec
+	Equal
+	Less
+	Greater
+	Assign
+	Not
+	Plus    // unitary +
+	Minus   // unitary -
+	Address // unitary &
+	Deref   // unitary *
+	NotEqual
+	LessEqual
+	GreaterEqual
+	Define
+	Ellipsis
+	Period
+	Tilde
+
+	// Separators
+	Comma
+	Semicolon
+	Colon
+
+	// Block tokens
+	ParenBlock   // (..)
+	BracketBlock // [..]
+	BraceBlock   // {..}
+
+	// Reserved keywords
+	Break
+	Case
+	Chan
+	Const
+	Continue
+	Default
+	Defer
+	Else
+	Fallthrough
+	For
+	Func
+	Go
+	Goto
+	If
+	Import
+	Interface
+	Map
+	Package
+	Range
+	Return
+	Select
+	Struct
+	Switch
+	Type
+	Var
+
+	// Internal tokens (no corresponding keyword)
+	Call
+	CallX
+	Label
+	JumpFalse
+	Enter // entering in function context
+	Exit  // exiting from function context
+)
+
+func (t TokenId) IsKeyword() bool  { return t >= Break && t <= Var }
+func (t TokenId) IsOperator() bool { return t >= Add && t <= Tilde }
+func (t TokenId) IsBlock() bool    { return t >= ParenBlock && t <= BraceBlock }