com.github.gchudnov.bscript.lang.ast

Access a field of a Struct

To access members of a struct like a.x, we trigger two ref operations. The first ref operation looks up a to figure out what type it is. The second ref then resolves x within a’s scope (upon seeing the . node). We match (possibly nested) member access expressions, e.g.:

   "a", "a.b", "a.b.c", and so on

Given «expr».x, member need’s «expr»’s type because it must look up x with the scope of «expr».

Addition

 a + b;

Logic And

 a AND b;

Annotation to apply to an AST element

Argument Declaration

Assigns a value to the variable that already exists.

 int x; // defined before

 x = 10 + 2; // assignment here

Binary Operation

 +, -, *, /

Block of code

Contains zero or more statements

 {
   int x;
   { ... } // <- nested block

   long y = { "alice"; 1 + 2; }; // here last value is returned and assigned to `y`
 }

Boolean Literal

 true, false

Method (Function) Call

 f(i);

Comment applied to AST

Compile Expression to reuse functionality implemented in JVM

The callback has a signature: Any => Either[Throwable, Any], inside of the callback there should be a pattern match and depending on the interpreter, Any is interpreted in a particular way, e.g. for InterpretVisitor: it is (InterpretState) => Either[Throwable, InterpretState]

Any Constant Variable

DateTime Literal

 "2007-12-03T10:15:30+01:00"

Date Literal

 2021-10-12

Decimal Literal

 3.3

Division

 a / b

Double Literal

 12.34

Equality Operation

 !=, ==

Equality

 ==

Expression

Expressions are a special kind of Statement.

Field Declaration in a Struct.

 struct X {
   int x;
   float y;
 }

Float Literal

 12.34f

Greater-Than

 >

Greater-Than OR Equal

 >=

Used for collections

Reference to an evalType

The type of the value computed by the expression

Reference to promoteToType

The type we need to promote current type to before evaluation. If None - the promotion is not needed.

Aggregates both evalType and promoteToType to enforce static typing.

Reference to a symbol

If Condition

 if(cond) then { ... } else { ... }
 if(cond) then { ... }

 int x = if(conf) then { 1+2; } else { 2*5; }

Initialization Node

Used to init variable to the default value.

 int x; // here in AST, Init() is used to initialize the int var to 0.

Int Literal

 12

Less-Than

 <

Less-Than OR Equal

 <=

Logic Operation

 AND, OR

Long Literal

 12

Method Declaration

Modulo

 a % b

Multiplication

 a * b

Not

 ! expr;

Not Equality

 !=

Logic Or

 a OR b;

Relational Operation

 <, >, <=, >=

Marks code, related to standard-library.

Used, for example, to prevent serialization of [std] functions.

String Literal

 "a"

Struct Declaration

Struct Initializer

 struct A {
   a: int
   b: string
 };

 A = { a: 1, b: "hello" };

Subtract

 a - b;

Unary Logic Operation

Unary Operation

Unary Minus

 -10

Reference to a variable

 x;

Variable Declaration

The AST for int i; would have VARDECL at the root and int and i as children.

 int x;
 float y = 10;

Collection (Vector)

 [1, 2, 3, 4, 5]

Void Literal