Quail-Language

Quail Specification

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Chapter 8: Statement executions

8.1 Common definitions

Throw - throw a Java exception

Raise - throw a Quail exception

RuntimeStriker - universal program flow interrupter. Used for break, continue, return, strike, throw

Overridable get/set - get/set from/to object that allows user to override get/set behaviour with _get/_set/_get_?/_set_? methods.

Every heading here is specified in form of NodeName (which syntax is applicable). Learn more about syntax in Chapter 2.

8.2 Runtime execution

8.2.1 Effects

8.2.1.1 AsyncNode (async effect)
  1. Async runtime worker created and started
8.2.1.2 EffectNode (any of the effects, except return and use)
8.2.1.3 InstructionNode (any instruction)
8.2.1.4 ReturnNode (return effect)

Return provided value

8.2.1.5 UseNode (use effect)

Load library with provided identifier (see Chapter 9) and place it into specified variable

8.2.2 Expression

Most of these operations are defined by and in type classes. They can raise various exceptions.

8.2.2.1 AssignNode (assignment operator)
8.2.2.2 BinaryOperatorNode (any of a <operator> b operators)
  1. Evaluate left and right parts
    • If singular operator: perform bin op
    • If array operator: unwrap lists, apply op to each pair. Raises UnsuitableTypeException and UnsuitableValueException if left or right operand is not a list, or if they sizes do not match. Returns resulting list.
    • If matrix operator: same as array, but does double unwrap. Returns resulting matrix
8.2.2.3 CallNode (any call)
  1. Determine callee and parent:
    • If is field call: parent and callee obtained
    • Else: only callee obtained
  2. Evaluate all args
  3. Evaluate all kwargs
  4. Call
    • If callee is func and parent is obtained and is field call:
      • If parent is dict and it contains callee in its pairs: perform usual call
      • Else if parent is not a prototype: Perform method call (pass this)
      • Else: Perform usual call
    • Else: Perform usual call
8.2.2.4 FieldReferenceNode (object.field)
  1. Obtain parent
  2. Get (overridable) provided field from parent
8.2.2.5 FieldSetNode (object.field = value)
  1. Obtain parent
  2. Set (overridable) provided field in parent
8.2.2.6 IndexingNode (object[index])
  1. Obtain parent
  2. Get at index from parent
8.2.2.7 IndexSetNode (object[index] = value)
  1. Obtain parent
  2. Set at index in parent
8.2.2.8 SubscriptNode (any subscript)
  1. Obtain parent and all not-null subscript parts (start, end, step)
  2. Perform subscript or stepped subscript on parent (based on whether step was provided or not)
8.2.2.9 TypecastNode (any typecast)
  1. Obtain conversion subject
  2. If conversion to:
    • num try to convert to num
    • string try to convert to string
    • bool try to convert to bool

    Else: Raise UnsupportedConversionException

8.2.2.10 UnaryOperatorNode (any <operator> a operator)

Same as 8.2.2.2 (BinaryOperatorNode), but with only one operand (which removes size equality check)

8.2.3 Generators

8.2.3.1 Pattern

All generators (8.2.3.2-8.2.3.5) fall for the same pattern:

  1. A new scope is created
  2. Generated dict/list created (empty for now)
  3. Generated dict/list is put in new scope under name _this
  4. Iterable is evaluated
  5. Iteration: (see also 8.2.5.2 and 8.2.5.5)
    • If condition is present and met or condition not present:
      1. Evaluate value or key-value pair
      2. Add value or key-value pair
  6. Return generated, destroy new scope
8.2.3.2 DictForGeneratorNode

See 8.2.3.1

8.2.3.3 DictThroughGeneratorNode

See 8.2.3.1

8.2.3.4 ListForGeneratorNode

See 8.2.3.1

8.2.3.5 ListThroughGeneratorNode

See 8.2.3.1

8.2.3.6 RangeNode
  1. Start, end and step object are evaluated.
  2. If any of there 3 are not numbers, UnsuitableTypeException raised.
  3. If step not manually provided:
    • If start <= end: step = 1
    • Else: step = -1
  4. Number iterator initialized with start value

  5. Iteration until:

    If range is including, < and > replaced with <= and >=

    If range is increasing (start <= end), condition is iterator </<= end, else iterator >/>= end.

    • Create new QNumber with current iterator value
    • Increment/decrement iterator
  6. Return generated range

8.2.4 Literals (values)

8.2.4.1 LiteralBool

Bool is evaluated

8.2.4.2 LiteralClass
  1. New scope is created
  2. Parent object is obtained (if not provided - Object)
  3. Every method in class is evaluated in the new scope
  4. Every field is put in the new scope
  5. Every other statement is executed in the new scope
  6. Inheritance is registered
  7. Object table is set to the new scope contents
  8. Place class into outer scope
8.2.4.3 LiteralDict

Every key-value pair evaluated and put into dict. Quail will try to convert every key to string (8.2.2.9)

8.2.4.4 LiteralFunction
  1. Arguments are initialized
  2. If current scope already contains a function with same name, evaluated function is treated as an alternative call to existing function
  3. Else - function is constructed and placed into scope

If function name is

8.2.4.5 LiteralLambda

Function is created and returned

8.2.4.6 LiteralList

Every value is evaluated and added to list. List is returned

8.2.4.7 LiteralNull

Null is returned

8.2.4.8 LiteralNum

Number is returned

8.2.4.9 LiteralStr

String is returned

8.2.5 Sections

8.2.5.1 BlockNode (sections / code blocks)

Every node in block is evaluated one-by-one sequentially

8.2.5.2 ForNode (for or every loops)
  1. Iterable is evaluated
  2. Start iteration called on iterable
  3. While there is more to iterate: call next iteration on iterable
8.2.5.3 IfNode
  1. Condition is evaluated
  2. If condition is true, appropriate statement executed; then IfNode ends

  3. If else if-s are present:

    For each else-if:

    1. Condition is evaluated
    2. If condition is true, appropriate statement executed; then IfNode ends
  4. If else is present - execute else
8.2.5.4 LoopStopNode (loop-stop when loop)
  1. Statement inside loop is executed
  2. Condition is evaluated
  3. If condition is true - quit cycle
  4. Go to 1
8.2.5.5 ThroughNode (through loop)
  1. Start, end, and step of loop are evaluated
  2. While iterator < end:
    1. Statement inside loop is executed
    2. Iterator is incremented by step
8.2.5.6 TryNode
  1. Statement inside try is being run
  2. If no exceptions were thrown, TryNode ends
  3. If there were exceptions, but there are no catch blocks - exceptions are suppressed, TryNode ends
  4. If catch blocks are present - do following for each block from top to bottom:
    1. If no class specified for catch block - execute it
    2. If class is specified - execute if exception is an instance of specified class
  5. If there were no suitable catch blocks, but they are present, exception is re-thrown
8.2.5.7 WhileNode
  1. Condition is evaluated
  2. If condition is false - quit cycle
  3. Statement inside loop is executed
  4. Go to 1

8.2.6 Variable

8.2.6.1 VariableNode (any variable reference)

If variable exists, its value is returned.

If not and variable node has modifiers, variable is being initialized according to the first modifier to an ‘empty’ synonym for that type: (e.g. num v -> initialize v to 0)