apg_py.lib.ast.Ast Class Reference

A class for capturing the AST as the parser traverses the parse tree. More...

Public Member Functions
def	__init__ (self, parser)
	Class constructor. More...
def	copy (self)
	Make a copy suitable for adding callback functions and doing translations. More...
def	add_callback (self, name, callback)
	Add a callback function to the named AST node. More...
def	down (self, name)
	Saves an AST record as the parser traverses down through a node with an assigned callback function. More...
def	up (self, name, phrase_index, phrase_length)
	Saves an AST record as the parser traverses up through a node with an assigned callback function. More...
def	save_state (self)
	Saves the state of the AST. More...
def	restore_state (self, state)
	Restores the AST to a previously saved state. More...
def	clear (self)
	Clear the AST for reuse by the parser. More...
def	translate (self, data=None)
	Do a depth-first traversal of the AST nodes, calling user-supplied callback functions 1) if a record for the node has been created and 2) if the user has attached a callback function to the node with Ast.add_callback(). More...

Public Attributes
	parser
	input
	indexStack
	records
	nodes

Detailed Description

A class for capturing the AST as the parser traverses the parse tree.

Definition at line 69 of file ast.py.

Constructor & Destructor Documentation

__init__()

def apg_py.lib.ast.Ast.__init__	(		self,
			parser
	)

Class constructor.

Parameters

parser

the parser object to attach this AST object to

Definition at line 72 of file ast.py.

Member Function Documentation

add_callback()

def apg_py.lib.ast.Ast.add_callback	(		self,
			name,
			callback
	)

Add a callback function to the named AST node.

Parameters

name

The name of the node to add the callback to.

callback

The callback function to add to the node. The function should have the prototype: fn(state, input, index, length, data) state - SEM_PRE for down, SEM_POST for up (see identifiers.py) input - the parser's input string as a tuple of integers/character codes index - the index of the first character of the matched phrase length - the number of characters in the matched phrase data - the user-supplied data (see Ast.translate()

Definition at line 109 of file ast.py.

clear()

def apg_py.lib.ast.Ast.clear

(

self

)

Clear the AST for reuse by the parser.

Definition at line 188 of file ast.py.

copy()

def apg_py.lib.ast.Ast.copy

(

self

)

Make a copy suitable for adding callback functions and doing translations.

This copy will not interact with the parser. The primary purpose of this is so the class ApgExp (exp.py) can internally do an AST translation of the parsed results and also return a copy of the AST for the user to do a separate, independent translation of the pattern-matched results.

Definition at line 86 of file ast.py.

down()

def apg_py.lib.ast.Ast.down	(		self,
			name
	)

Saves an AST record as the parser traverses down through a node with an assigned callback function.

Parameters

name	The rule or UDT name of the node.

Definition at line 125 of file ast.py.

restore_state()

def apg_py.lib.ast.Ast.restore_state	(		self,
			state
	)

Restores the AST to a previously saved state.

Should be called by the RNM operators, for example, if the branch below fails.

Parameters

state

the return value of a previous call to Ast.save_state()

Definition at line 178 of file ast.py.

save_state()

def apg_py.lib.ast.Ast.save_state

(

self

)

Saves the state of the AST.

Should be called by the RNM operators so that the state can be restored should the branch below fail. The state is a list saving off the length of the list of records and the index stack.

Definition at line 170 of file ast.py.

translate()

def apg_py.lib.ast.Ast.translate	(		self,
			data = None
	)

Do a depth-first traversal of the AST nodes, calling user-supplied callback functions 1) if a record for the node has been created and 2) if the user has attached a callback function to the node with Ast.add_callback().

Parameters

data	User-supplied data which is made available to the callback functions but is otherwise ignored by the AST.

Definition at line 193 of file ast.py.

up()

def apg_py.lib.ast.Ast.up	(		self,
			name,
			phrase_index,
			phrase_length
	)

Saves an AST record as the parser traverses up through a node with an assigned callback function.

Completes the matching "down" record with the information that was not available during the downward traversal of the node.

Parameters

name	The rule or UDT name of the node.
phrase_index	Index of the first input character of the matched phrase.
phrase_length	The number of input characters matched.

Definition at line 144 of file ast.py.

Member Data Documentation

indexStack

apg_py.lib.ast.Ast.indexStack

Definition at line 78 of file ast.py.

input

apg_py.lib.ast.Ast.input

Definition at line 77 of file ast.py.

nodes

apg_py.lib.ast.Ast.nodes

Definition at line 80 of file ast.py.

parser

apg_py.lib.ast.Ast.parser

Definition at line 75 of file ast.py.

records

apg_py.lib.ast.Ast.records

Definition at line 79 of file ast.py.

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The documentation for this class was generated from the following file:

• apg_py/lib/ast.py