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- builtins.object
-
- Evaluator
class Evaluator(builtins.object) |
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Evaluator(config=None)
Evaluator class
Evaluate statement.
Attributes:
_config (Config or NoneType): Configuration
_environment (Environment): Environment instance that is used
to read/write variable.
_binary_operations (dict): Token type -> method
_assign_operations (dict): Token type -> method
_stack (list[dict]): Stack of evaluated statement.
There are two purposes.
- Keep limit of the recursive called
times.
- Avoid software runaway.
The each element is a dict that have
2 strings.
- "name": Block type or the class name
of evaluated statement.
- "detail": The detail of evaluated
statement.
_max_array_size (int): Maximum array/block size
_max_depth (int): Maximum recursive called times of evaluate
method
_max_loop_times (int): Maximum loop times of "for", "while",
and so on.
_REPLACED_LETTERS (dict): The escaped letter and real letter.
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Methods defined here:
- __init__(self, config=None)
- Initialize class.
Args:
config (Config or NoneType): Configuration if needed.
- evaluate(self, statement)
- Evaluate statement.
This should not be called. Sub-class, such as Identifier,
should be called.
Args:
statement (Statement): The evaluated statement
Raises:
EvaluateError: This exception always happen when this
method is called.
- get(self, name)
- Get a variable's value.
Args:
name (str): Variable name
Returns:
Any: Its value
Environment.UNDEFINED is returned if the given name's
variable is not existed.
Raises:
EvaluateError: It is happen if the given name isn't string.
- rewind_after_abort(self)
- Rewinds stack and environment after abort.
Fix as below. This is clean up for abort (exception).
When Viv.run_method is failed, instance has unnecessary
information. It may be happen unusual behavior in the next
running via its instance. So clean up is needed.
- Reset stack of evaluated statement "{@link #stack}".
- Rewind environment "{@link #environment}" to first hierarchy.
Note that it is assumed that the first call of evaluate method
is evaluate(self, block: Block).
For example,
- The newest Environment #1 : The present position
- enclosing = #2 |
- Environment #2 |
- enclosing = #3 V
- Environment #3 : Rewind to this position.
(This is made by Block statement of making Instance.)
- enclosing = #4
- Instance's member variable is available.
- Instance's method is available.
- Root Environment #4
- enclosing = null
- set(self, name, value)
- Set a variable.
Args:
name (str): Variable name
value (Any): Its value
Raises:
EvaluateError: It is happen if the given name isn't string.
Static methods defined here:
- is_truthy(value) -> bool
- Evaluate as boolean.
Args:
value (Any): A value that is evaluated as boolean.
Returns:
bool: The evaluated result
- None, False, 0, 0.0 --> False
- Other --> True
(Note that "0" is True.)
- make_str(value, config=None, is_member=False, is_escape=True)
- Make string from any value.
In this class, values are treated as Python native values.
There are the following difference between VivJson and
Python.
- null : None
- true : True
- false : False
Thus, this method is used instead of str function of Python.
Args:
value (Any): A value for converting to string.
int, float, bool, str, list, dict, None, or
Statement.
config (Config or NoneType, optional): Configuration if
needed.
is_member (bool, optional): True if the above value is a
member of block or array,
False otherwise.
The default is False.
is_escape (bool, optional): True if escape sequence is
enabled, False otherwise.
When this is True, control
character, the double
quotation mark, or reverse
solidus is modified as
escape sequence.
The default is True.
Returns:
str: The given value as string
Raises:
EvaluateError: It is happen if number is Infinity or NaN
without permission of Configuration.
Data descriptors defined here:
- __dict__
- dictionary for instance variables (if defined)
- __weakref__
- list of weak references to the object (if defined)
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