visitor.h File Reference

AST visitors. More...

#include "ast.h"

Go to the source code of this file.

Classes
struct	NodeVisitor
	Node visitor structure. More...

Typedefs
typedef struct NodeVisitor	NodeVisitor
	Node visitor structure.

Functions
NodeVisitor *	NodeVisitor_new (void)
	Allocate a new generic visitor structure.
void	NodeVisitor_traverse (NodeVisitor *visitor, ASTNode *node)
	Perform an AST traversal using the given visitor.
void	NodeVisitor_traverse_and_free (NodeVisitor *visitor, ASTNode *node)
	Perform an AST traversal using the given visitor and then deallocate the visitor.
void	NodeVisitor_free (NodeVisitor *visitor)
	Deallocate a visitor structure.
NodeVisitor *	PrintVisitor_new (FILE *output)
	Create a new AST debug print visitor.
NodeVisitor *	GenerateASTGraph_new (FILE *output)
	Create a new AST debug graph output visitor.
NodeVisitor *	SetParentVisitor_new (void)
	Create a new visitor that sets up parent pointers as attributes.
NodeVisitor *	CalcDepthVisitor_new (void)
	Create a new visitor that calculates node depths as attributes.

Detailed Description

AST visitors.

This module provides declarations of AST visitors. It is not strictly necessary to understand these for Project 2 (parsing), but they are included because the debug output is implemented as a visitor. The declarations in this file will be will be critical for Projects 3 (static analysis) and 4 (code generation).

Typedef Documentation

NodeVisitor

typedef struct NodeVisitor NodeVisitor

Node visitor structure.

A visitor is basically a collection of function pointers that are invoked as the visitor traverses the AST.

Function Documentation

CalcDepthVisitor_new()

NodeVisitor * CalcDepthVisitor_new

(

void

)

Create a new visitor that calculates node depths as attributes.

These depths are used during debug output.

Returns

Pointer to visitor structure

GenerateASTGraph_new()

NodeVisitor * GenerateASTGraph_new

(

FILE *

output

)

Create a new AST debug graph output visitor.

The output is in DOT format: https://graphviz.org

To convert the output to a PNG (for example):

dot -Tpng -o ast.png ast.dot

Parameters

output

File stream for the DOT output

Returns

Pointer to visitor structure

NodeVisitor_free()

void NodeVisitor_free

(

NodeVisitor *

visitor

)

Deallocate a visitor structure.

Parameters

visitor

Visitor to deallocate

NodeVisitor_new()

NodeVisitor * NodeVisitor_new

(

void

)

Allocate a new generic visitor structure.

Returns

A pointer to the allocated visitor

NodeVisitor_traverse()

void NodeVisitor_traverse	(	NodeVisitor *	visitor,
		ASTNode *	node
	)

Perform an AST traversal using the given visitor.

Parameters

visitor	Visitor structure containing function pointers that will be invoked during the traversal
node	Root of AST structure to traverse

NodeVisitor_traverse_and_free()

void NodeVisitor_traverse_and_free	(	NodeVisitor *	visitor,
		ASTNode *	node
	)

Perform an AST traversal using the given visitor and then deallocate the visitor.

This is provided as a shortcut so that traversals can be written as a single line in the compiler driver routine. For example:

NodeVisitor_traverse_and_free(PrintVisitor_new(stdout), tree);

Parameters

visitor	Visitor structure containing function pointers that will be invoked during the traversal
node	Root of AST structure to traverse

PrintVisitor_new()

NodeVisitor * PrintVisitor_new

(

FILE *

output

)

Create a new AST debug print visitor.

Parameters

output

File stream for the print output

Returns

Pointer to visitor structure

SetParentVisitor_new()

NodeVisitor * SetParentVisitor_new

(

void

)

Create a new visitor that sets up parent pointers as attributes.

These parent pointers are used in other visitors.

Returns

Pointer to visitor structure