titus.pfaast.Ast¶

class titus.pfaast.Ast[source]¶

Bases: object

Abstract base class for a PFA abstract syntax tree.

collect(pf)¶

Walk over tree applying a partial function, returning a list of results in its domain.

Parameters:	pf (callable with isDefinedAt method) – partial function that takes any titus.pfaast.Ast as an argument, returning anything pf.isDefinedAt (callable) – domain that takes any titus.pfaast.Ast as an argument, returning True if this item is in the domain, False otherwise
Return type:	list of function results
Returns:	a result for each abstract syntax tree node in the pf function’s domain

jsonNode(lineNumbers, memo)¶

Convert this abstract syntax tree to Pythonized JSON.

Parameters:	lineNumbers (bool) – if True, include locator marks in each JSON object memo (set of string) – used to avoid recursion; provide an empty set if unsure
Return type:	Pythonized JSON
Returns:	JSON representation

replace(pf)¶

Walk over tree applying a partial function, returning a transformed copy of the tree.

Parameters:	pf (callable with isDefinedAt method) – partial function that takes any titus.pfaast.Ast as an argument, returning a replacement titus.pfaast.Ast pf.isDefinedAt (callable) – domain that takes any titus.pfaast.Ast as an argument, returning True if this item is in the domain, False otherwise
Return type:	new titus.pfaast.Ast tree
Returns:	tree with nodes in the pf function’s domain transformed; everything else left as-is

startDict(lineNumbers)¶

Helper function to build a Pythonized JSON object.

Parameters:	lineNumbers (bool) – if True, include the locator mark
Return type:	OrderedDict
Returns:	an empty Pythonized JSON object or one containing only the locator mark

toJson(lineNumbers=True)¶

Serialize this abstract syntax tree as a JSON string.

Parameters:	lineNumbers (bool) – if True, include locator marks at the beginning of each JSON object
Return type:	string
Returns:	JSON string

walk(task, symbolTable, functionTable, engineOptions, version)¶

Walk over tree applying a titus.pfaast.Task while checking for semantic errors.

This is how Python is generated from an abstract syntax tree: the titus.pfaast.Task in that case is titus.genpy.GeneratePython.

Parameters:	task (titus.pfaast.Task) – generic task to perform on this abstract syntax tree node’s context symbolTable (titus.pfaast.SymbolTable) – used to look up symbols, cells, and pools functionTable (titus.pfaast.FunctionTable) – used to look up functions engineOptions (titus.options.EngineOptions) – implementation options version (titus.signature.PFAVersion) – version of the PFA language in which to interpret this PFA
Return type:	(titus.pfaast.AstContext, titus.pfaast.TaskResult)
Returns:	(information about this abstract syntax tree node after type-checking, result of the generic task)