NBInterpolatedString Class Reference

A wrapper for NBString::Interpolate() ideal for easy access to ephemeral values. More...

#include <nbstring.h>

Inherits NBString.

Public Member Functions
	NBInterpolatedString ()
	Construct a NBInterpolatedString object.
	NBInterpolatedString (const NBString &str)
	Construct a new NBInterpolatedString object from an existing NBInterpolatedString object.
	NBInterpolatedString (const NBString &str, size_t pos, size_t len=npos)
	Construct a new NBInterpolatedString object from a substring of an existing NBInterpolatedString object.
	NBInterpolatedString (const char *s)
	Construct a NBInterpolatedString object from a character string (null terminated array of characters)
	NBInterpolatedString (const char *s, size_t n)
	Construct a NBInterpolatedString object from a character string up to the specified amount.
	~NBInterpolatedString ()
	NBInterpolatedString destructor.
NBString &	Append (const char *str, size_t len)
	Append a string to an existing NBString object.
NBString &	FdAppend (int fd, size_t len)
	Append from a file descriptor to an existing NBString object.
NBInterpolatedString &	Interpolate ()
	Perform a string interpolation in-place. This allows NBStrings to easily access the NetBurner Config System, as in:
Public Member Functions inherited from NBString
	NBString ()
	Construct a NBString object.
	NBString (const NBString &str)
	Construct a new NBString object from an existing NBString object.
	NBString (const NBString &str, size_t pos, size_t len=npos)
	Construct a new NBString object from a substring of an existing NBString object.
	NBString (const char *s)
	Construct a NBString object from a character string (null terminated array of characters)
	NBString (const char *s, size_t n)
	Construct a NBString object from a character string up to the specified amount.
	NBString (const JsonRef &jr)
	Construct a NBString object using the current string referenced by a JsonRef. This allows for using Large Strings without an intermediate malloc in the JsonParser.
	~NBString ()
	NBString destructor.
const char *	c_str () const
	Method to pass a NBString as a constant char *.
NBString	substr (size_t pos=0, size_t len=npos) const
	Creates a new NBString object from a substring of the existing NBString object.
int	compare (const NBString &str) const
	Compares two NBString objects.
int	compare (const char *s) const
	Compares the NBString object to a character string.
size_t	find (const NBString str, size_t pos=0) const
	Find a substring within a NBString object.
size_t	find (const char *str, size_t pos=0) const
	Find a substring within a character string.
size_t	find (const char *s, size_t pos, size_t n) const
	Find a substring within a character string.
size_t	find (char c, size_t pos=0) const
	Find the first occurence of a character within the NBString object.
size_t	replace (const char *findStr, char rep, size_t startPos=0, size_t end=0)
	Replace all occurrences of all "<findStr>" characters within the NBString object.
size_t	replace (char c, char rep, size_t startPos=0, size_t end=0)
	Replace all occurrences of all "<findStr>" characters within the NBString object.
void	shrink (int n)
	Reduces the length of the string by n.
size_t	size () const
	Returns the current size of memory allocated for the string.
size_t	length () const
	Returns the length of the string.
void	clear ()
	Clear a NBString object and free allocated memory.
bool	empty () const
	Check if a string is empty.
NBString &	Append (const char *str, size_t len)
	Append a string to an existing NBString object.
NBString &	FdAppend (int fd, size_t len)
	Append from a file descriptor to an existing NBString object.
NBString &	Reserve (size_t len)
	Reserve an additional buffer amount.
int	vsiprintf (const char *format, va_list &vl)
	Print to a string with formatting.
int	sprintf (const char *format,...)
	sprintf to a string with formatting to a character array
int	sprintf (NBString const format,...)
	sprintf to a string with formatting as a NBString object
int	siprintf (const char *format,...)
	isprintf (integer) to a string with formatting to a character array
int	siprintf (NBString const format,...)
	isprintf (integer) to a string with formatting to a NBString object
int	stoi () const
	Parse the string and convert to an integer number.
long	stol () const
	Parse the string value and convert to a long integer number.
unsigned int	stoui () const
	Parse the string value and convert to a const integer number.
unsigned long	stoul () const
	Parse the string value and convert to a const unsigned long integer number.
double	stod () const
	Parse the string value and convert to a const double float number.
IPADDR	to_ipaddr () const
	Parse the string value and convert to an IPADDR IP address.
size_t	copy (char *s, size_t len, size_t pos=0) const
	Copy a substring, does not null terminate.
size_t	strcopy (char *s, size_t len, size_t pos=0) const
	Copy a substring, with null termination.
bool	Interpolate (NBString &dest)
	Perform a string interpolation and place the finished interpolation in the Destination string. This allows NBStrings to easily access the NetBurner Config System, as in:
bool	Interpolate ()
	Perform an in-place string interpolation. This allows NBStrings to easily access the NetBurner Config System, as in:

Detailed Description

A wrapper for NBString::Interpolate() ideal for easy access to ephemeral values.

The NetBurner string interpolation system is a powerful and easy way to read system data and should be used carefully. For example, it would be unwise to allow untrusted user input to affect these interpolation commands, in case there is any information in the Config system that you don't want public. Normal sanity checking of regular user input is also advisable.

Syntax is similar to vim or ex commands, but simplified. There are currently two commands:

• d deletes matching substrings
• s replaces matching substrings

{ and } surround the interpolation command including any Config system variable name/path. Colons separate names, commands, and arguments. Semicolons allow command chaining. {{ or }} are escaped curly braces. \: can escape colons (actually "\\:" when writing C++ code, since \ is also a C++ escape character)

For example, if the config variable AppData.foo is "a_b_c_d", then

NBInterpolatedString example("{AppData.foo:d:_;}");
example.Interpolate();

Would result in example equalling "abcd".

Commands can be chained with ; – if the config variable AppData.foo is "2_3_4_5es", then

NBInterpolatedString example("{AppData.foo:d:_;s:2345:potato;}");
example.Interpolate();

Would result in example equalling "potatoes".

Commands are processed from left to right. If the config same variable AppData.foo of "2_3_4_5es" is interpolated like this:

NBInterpolatedString example("{AppData.foo:s:2345:potato;d:_;}");
example.Interpolate();

It would instead would yield "2345es".

In our PubSub, Config, and SubHandler MQTT examples, we remove the first three octets of a known MAC address as well as the remaining semicolons with an interpolator like this: {Sys.NetIf.Ethernet0.MAC:d:00\\:03\\:F4\\:;d:\\:}

In order, this is does the following:

• Sys.NetIf.Ethernet0.MAC obtains the matching Config string (visible at http://<your device ip or hostname>:20034/UI.html)
• : separates commands from config variable path
• d: delete the following literal substring:
• 00\\:03\\:F4\\: "00:03:F4:"
• ; end command, begin new command with previous command's output as input
• d: delete the following literal substring:
• \\: any/all colons remaining in the string

Thus a MAC address like 00:03:F4:12:34:56 will become 123456 in the resulting output.

Constructor & Destructor Documentation

NBInterpolatedString() [1/4]

NBInterpolatedString::NBInterpolatedString

(

const NBString &

str

)

Construct a new NBInterpolatedString object from an existing NBInterpolatedString object.

Parameters

str	Existing NBInterpolatedString object

NBInterpolatedString() [2/4]

NBInterpolatedString::NBInterpolatedString	(	const NBString &	str,
		size_t	pos,
		size_t	len = npos )

Construct a new NBInterpolatedString object from a substring of an existing NBInterpolatedString object.

Parameters

str	Existing NBInterpolatedString object
pos	Starting position to copy
len	Ending position to copy

NBInterpolatedString() [3/4]

NBInterpolatedString::NBInterpolatedString

(

const char *

s

)

Construct a NBInterpolatedString object from a character string (null terminated array of characters)

Parameters

s	String to initialize object

NBInterpolatedString() [4/4]

NBInterpolatedString::NBInterpolatedString	(	const char *	s,
		size_t	n )

Construct a NBInterpolatedString object from a character string up to the specified amount.

Parameters

s	String to initialize object
n	Number of characters to copy

Member Function Documentation

Append()

NBString & NBInterpolatedString::Append	(	const char *	str,
		size_t	len )

Append a string to an existing NBString object.

Append a string to an existing NBString object

Parameters

str	String to append
len	Number of characters to append

Returns

The updated NBString object

FdAppend()

NBString & NBInterpolatedString::FdAppend	(	int	fd,
		size_t	len )

Append from a file descriptor to an existing NBString object.

Append from a file descriptor to an existing NBString object

Parameters

fd	File descriptor to append from
len	Number of characters to append

Returns

The updated NBString object

Interpolate()

NBInterpolatedString & NBInterpolatedString::Interpolate

(

)

Perform a string interpolation in-place. This allows NBStrings to easily access the NetBurner Config System, as in:

NBInterpolatedString test("My MAC: {Sys.NetIf.Ethernet0.MAC} \n");
test.Interpolate();

See also

NBString::Interpolate()

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

• nbstring.h