parse.cpp File Reference

#include "parse.hpp"

Functions
bool	iswhitespace (char ch)
	Check whether the character is whitespace.
bool	is_legalnumeric (string str)
	Check whether numericstr is an legal numericstr string.
bool	is_legaloperator (string str)
	Check whether str is a legal operator.
void	readsinglesymbol (string &substring, string &sexpr)
void	clearwhitespace (string &sexpr)
	Clear the whitespace at the begining and end of string sexpr.
bool	is_legalexpr (string sexpr)
	Check whether the s-expression legal.
Cell *	makecell (string str)
	Make the cell.
Cell *	separate_parse (string &instr)
	Separately parse the sexpr and build the tree.
Cell *	parse (string sexpr)
	Recursively parse sexpr and build the parse tree.
Variables
bool	inparsecar

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Detailed Description

Implementation of a parser that analyzes a string containing an s-expression, and determines its tree structure.

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Function Documentation

void clearwhitespace

(

string &

sexpr

)

Clear the whitespace at the begining and end of string sexpr.

Parameters:

sexpr

The string.

References iswhitespace().

Referenced by is_legalexpr(), parse(), and separate_parse().

bool is_legalexpr

(

string

sexpr

)

Check whether the s-expression legal.

References clearwhitespace(), is_legalnumeric(), and is_legaloperator().

Referenced by parse().

bool is_legalnumeric

(

string

str

)

Check whether numericstr is an legal numericstr string.

Parameters:

str

The string to be checked

Returns:

ture if numericstr is an legal numericstr string, false otherwise

Referenced by is_legalexpr(), and makecell().

bool is_legaloperator

(

string

str

)

Check whether str is a legal operator.

Referenced by is_legalexpr(), and makecell().

bool iswhitespace

(

char

ch

)

Check whether the character is whitespace.

Returns:

True if it is character, false else.

Parameters:

ch

The character to check.

Referenced by clearwhitespace(), readfile(), readsinglesymbol(), and separate_parse().

Cell* makecell

(

string

str

)

Make the cell.

Parameters:

str

The string to represent the symbol, int or double.

References is_legalnumeric(), is_legaloperator(), make_double(), make_int(), and make_symbol().

Referenced by parse().

Cell* parse

(

string

sexpr

)

Recursively parse sexpr and build the parse tree.

Parameters:

sexpr

The s-expression stored in a string variable (note that this version of parse has side effects: it may alter the contents of sexpr).

Returns:

A pointer to the conspair cell at the root of the parse tree.

References clearwhitespace(), is_legalexpr(), makecell(), nil, and separate_parse().

Referenced by parse_eval_print(), and separate_parse().

void readsinglesymbol	(	string &	substring,
		string &	sexpr
	)

References iswhitespace().

Cell * separate_parse

(

string &

instr

)

Separately parse the sexpr and build the tree.

Parameters:

instr

The string which consists of s-expressions.

Returns:

A pointer to the conspair cell at the root of the parse tree.

References car(), cdr(), clearwhitespace(), cons(), inparsecar, iswhitespace(), nil, parse(), and readsinglesymbol().

Referenced by parse().

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Variable Documentation

bool inparsecar

Referenced by separate_parse().