casa::ImageExprParse Class Reference

Class to hold values from image expression parser. More...

#include <ImageExprParse.h>

List of all members.

Public Member Functions
	ImageExprParse (Bool value)
	Construct a literal object for the given type.
	ImageExprParse (Int value)
	ImageExprParse (Float value)
	ImageExprParse (Double value)
	ImageExprParse (const Complex &value)
	ImageExprParse (const DComplex &value)
	ImageExprParse (const Char *value)
	ImageExprParse (const String &value)
LatticeExprNode	makeFuncNode () const
	Make a LatticeExprNode for a function.
LatticeExprNode	makeFuncNode (const LatticeExprNode &arg1) const
LatticeExprNode	makeFuncNode (const LatticeExprNode &arg1, const LatticeExprNode &arg2) const
LatticeExprNode	makeFuncNode (const LatticeExprNode &arg1, const LatticeExprNode &arg2, const LatticeExprNode &arg3) const
LatticeExprNode	makeLRNode () const
	Make a LatticeExprNode object for the lattice or region name.
LatticeExprNode	makeLitLRNode () const
	Make a LatticeExprNode object for the name of constant, lattice, or region.
LatticeExprNode	makeRegionNode () const
	Make a LatticeExprNode object for the temporary region number.
LatticeExprNode	makeLiteralNode () const
	Make a LatticeExprNode object for the literal value.
Static Public Member Functions
static LatticeExprNode	command (const String &str, const String &dirName=String())
	Parse the given command.
static LatticeExprNode	command (const String &str, const Block< LatticeExprNode > &tempLattices, const PtrBlock< const ImageRegion * > &tempRegions, const String &dirName=String())
static Slice *	makeSlice (const ImageExprParse &start)
	Make a Slice object from 1-3 literals.
static Slice *	makeSlice (const ImageExprParse &start, const ImageExprParse &end)
static Slice *	makeSlice (const ImageExprParse &start, const ImageExprParse &end, const ImageExprParse &incr)
static LatticeExprNode	makeIndexinNode (const LatticeExprNode &axis, const vector< Slice > &slices)
	Make a node for the INDEXIN function.
static LatticeExprNode	makeValueList (const Block< LatticeExprNode > &values)
	Make an array from a value list.
static IPosition	makeBinning (const LatticeExprNode &values)
	Make an IPosition containing the binning values.
static void	setNode (const LatticeExprNode &node)
	Set the static node object (used by the .y file).
static void	addNode (LatticeExprNode *node)
	Keep track of the nodes allocated while parsing the expression.
static void	addNode (ImageExprParse *node)
static void	deleteNodes ()
static String	setAddDir (const String &dirName, const String &fileName)
	A function to test addDir.
Private Member Functions
Bool	tryLatticeNode (LatticeExprNode &node, const String &name) const
	Try if the name represent a lattice or image.
LatticeExprNode	makeImageNode (const String &name, const String &mask) const
	Make the node from the image name and a mask name.
Static Private Member Functions
static String	addDir (const String &fileName)
	If a directory was given, prepend it to the file name if relative.
static Table &	getRegionTable (void *, Bool)
	Callback function for RegionHandlerTable to get the table to be used.
static const CountedPtr < HDF5File > &	getRegionHDF5 (void *)
	Callback function for RegionHandlerHDF5 to get the file to be used.
Private Attributes
DataType	itsType
Bool	itsBval
Int	itsIval
Float	itsFval
Double	itsDval
Complex	itsCval
DComplex	itsDCval
String	itsSval
Static Private Attributes
static LatticeExprNode	theirNode

---

Detailed Description

Class to hold values from image expression parser.

Intended use:

Public interface

Prerequisite

• LatticeExpr

Etymology

ImageExprParse is the class used to parse an image expression command.

Synopsis

ImageExprParse is used by the parser of image expression statements. The parser is written in Bison and Flex in files ImageExprGram.y and .l. The statements in there use the routines in this file to act upon a reduced rule.

The main function (and the only function to be used by a user) is the static function ImageExprParse::command which parses an expression command. It returns a LatticeExprNode object containing the expression represented as a tree. The object can be used as a Lattice(Expr)<T> in other operations.

The syntax of the command is similar to that of expressions in C++. E.g.

      min(img1, img2) + sin(img3)

The following items can be used in an expression:

• Binary operators +, -, *, /, % (modulo), and ^ (power).
• Unary operators + and -.
• Comparison operators ==, >, >=, <, <=, and !=.
• Logical operators &&, ||, and !.
• Constant single and double precision values.
  No exponent or exponent "e" results in single precision (Float), while "d" results in double precision (Double).
• The imaginary part of a complex value can be given by the suffix "i". A full complex number can be given by addition. E.g. "3+4i". The complex is single (Complex) or double (DComplex) precision depending on the constituting parts.
• The special constants pi and e can be given as a double precision value by means of the functions pi() and e().
• Boolean constants T and F can be given.
• A lot of functions are available. They are the same as the ones supported by class LatticeExprNode .
• Explicit conversion functions float, double, complex and dcomplex are available. Conversions are automatically done where needed, but for performance reasons it may sometimes be better to do explicit conversions. See also below in the first example.
• An image can to be given using its file name. The file name can contain environment variables and user home directories using the standard UNIX syntax $ENVVAR and ~username. There are 3 ways to specify a file name:
  1. When the name contains no other special characters than $, ~, and . it can be given as such.
  2. Backslashes can be used to escape individual special characters.
  3. The full name can be enclosed in quotes (single or double) to escape the entire name. Adjacent quoted parts are combined to one name, which can be used to use quotes in the file name.
  Note that escaping has to be used too for the file name T or F (otherwise it is the boolean constant). E.g.

               image.data
               "~noordam/data/image.data"
               "~/image.data"
               "$HOME/image.data"
               $HOME\/image.data
               "ab'c"'d"e'          results in  ab'cd"e
  

  Only input images with data type Float and Complex are supported, because those data types are the only ones used so far. Support of Bool, Double, and DComplex is very simple to build in. The resulting lattice can be of type Bool, Float, Double, Complex, and DComplex.
• An image can also be given by means of the $n notation, where n is the sequence number in the tempLattices argument given to the command function. Note that the sequence numbers start counting at 1 (to be compliant with glish indexing).
  It can, for instance, be used to use non-persistent lattices in an expression.

When the expression is parsed, it is checked if the images and lattices involved have conforming shapes and coordinates. Note, however, that some functions (e.g. mean) reduce an image to a scalar. Such an image can have a different shape and coordinates.

The data types of the images and constants involved can be different. The data type of a subexpression is the common data type (e.g. Float and Double result in Double; Complex and Double result in DComplex). Automatic implicit conversions are done where needed. However, for performance reasons it may sometimes be better to convert explicitly. See below in the first example.

The expression evaluator (which is not part of the parser) evaluates the expression in chunks to avoid having to keep large temporary results. A scalar subexpression is evaluated only once to avoid unnecessary (possibly expensive) calculations.

Some examples:

img1 + min(float(pi()), mean(img2))

Suppose img1 and img2 are images with single precision data. They do not need to have conforming shapes and coordinates, because only the mean of img2 is used.
Note that pi is explicitly converted to single precision, because pi() results in a Double. If that was not done, the expression result would be a Double with the effect that all data of img1 had to be converted to Double.

min(img1, (min(img1)+max(img1))/2)

This example shows that there are 2 min functions. One with a single argument returning the minimum value of that image. The other with 2 arguments returning a lattice containing img1 data clipped at the value of the 2nd argument.

Example

       LatticeExpr<Double> expr ("a + sin(b)");
       ArrayLattice<Double> arr(expr.shape());
       arr.copyData (expr);

Line 1 creates a LatticeExpr object for the given expression. Note that a and b are names of lattice files (e.g. PagedImage).
Line 2 creates an ArrayLattice with the same shape as the expression (which is the shape of lattice a (and b)).
Line 3 copies the result of the expression to the ArrayLattice.

Motivation

It is necessary to be able to give an image expression command in ASCII. This can be used in glish to operate on lattices/images.

Definition at line 204 of file ImageExprParse.h.

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Constructor & Destructor Documentation

casa::ImageExprParse::ImageExprParse

(

Bool

value

)

Construct a literal object for the given type.

casa::ImageExprParse::ImageExprParse

(

Int

value

)

casa::ImageExprParse::ImageExprParse

(

Float

value

)

casa::ImageExprParse::ImageExprParse

(

Double

value

)

casa::ImageExprParse::ImageExprParse

(

const Complex &

value

)

casa::ImageExprParse::ImageExprParse

(

const DComplex &

value

)

casa::ImageExprParse::ImageExprParse

(

const Char *

value

)

casa::ImageExprParse::ImageExprParse

(

const String &

value

)

---

Member Function Documentation

static String casa::ImageExprParse::addDir

(

const String &

fileName

)

[static, private]

If a directory was given, prepend it to the file name if relative.

static void casa::ImageExprParse::addNode

(

LatticeExprNode *

node

)

[static]

Keep track of the nodes allocated while parsing the expression.

static void casa::ImageExprParse::addNode

(

ImageExprParse *

node

)

[static]

static LatticeExprNode casa::ImageExprParse::command	(	const String &	str,
		const String &	dirName = String()
	)		[static]

Parse the given command.

It will open all lattices needed. It returns the resulting image expression.
The tempLattices/tempRegions arguments make it possible to use temporary lattices/images and regions in the expression by means of the $n notation.
If a directory name is given, it is used instead of the working directory for relative file names.

static LatticeExprNode casa::ImageExprParse::command	(	const String &	str,
		const Block< LatticeExprNode > &	tempLattices,
		const PtrBlock< const ImageRegion * > &	tempRegions,
		const String &	dirName = String()
	)		[static]

static void casa::ImageExprParse::deleteNodes

(

)

[static]

static const CountedPtr<HDF5File>& casa::ImageExprParse::getRegionHDF5

(

void *

)

[static, private]

Callback function for RegionHandlerHDF5 to get the file to be used.

static Table& casa::ImageExprParse::getRegionTable	(	void *	,
		Bool
	)		[static, private]

Callback function for RegionHandlerTable to get the table to be used.

static IPosition casa::ImageExprParse::makeBinning

(

const LatticeExprNode &

values

)

[static]

Make an IPosition containing the binning values.

LatticeExprNode casa::ImageExprParse::makeFuncNode

(

)

const

Make a LatticeExprNode for a function.

LatticeExprNode casa::ImageExprParse::makeFuncNode

(

const LatticeExprNode &

arg1

)

const

LatticeExprNode casa::ImageExprParse::makeFuncNode	(	const LatticeExprNode &	arg1,
		const LatticeExprNode &	arg2
	)		const

LatticeExprNode casa::ImageExprParse::makeFuncNode	(	const LatticeExprNode &	arg1,
		const LatticeExprNode &	arg2,
		const LatticeExprNode &	arg3
	)		const

LatticeExprNode casa::ImageExprParse::makeImageNode	(	const String &	name,
		const String &	mask
	)		const [private]

Make the node from the image name and a mask name.

The mask name can be NOMASK (case insensitive) meaning that no mask is applied to the image.

static LatticeExprNode casa::ImageExprParse::makeIndexinNode	(	const LatticeExprNode &	axis,
		const vector< Slice > &	slices
	)		[static]

Make a node for the INDEXIN function.

LatticeExprNode casa::ImageExprParse::makeLiteralNode

(

)

const

Make a LatticeExprNode object for the literal value.

LatticeExprNode casa::ImageExprParse::makeLitLRNode

(

)

const

Make a LatticeExprNode object for the name of constant, lattice, or region.

LatticeExprNode casa::ImageExprParse::makeLRNode

(

)

const

Make a LatticeExprNode object for the lattice or region name.

LatticeExprNode casa::ImageExprParse::makeRegionNode

(

)

const

Make a LatticeExprNode object for the temporary region number.

static Slice* casa::ImageExprParse::makeSlice

(

const ImageExprParse &

start

)

[static]

Make a Slice object from 1-3 literals.

static Slice* casa::ImageExprParse::makeSlice	(	const ImageExprParse &	start,
		const ImageExprParse &	end
	)		[static]

static Slice* casa::ImageExprParse::makeSlice	(	const ImageExprParse &	start,
		const ImageExprParse &	end,
		const ImageExprParse &	incr
	)		[static]

static LatticeExprNode casa::ImageExprParse::makeValueList

(

const Block< LatticeExprNode > &

values

)

[static]

Make an array from a value list.

static String casa::ImageExprParse::setAddDir	(	const String &	dirName,
		const String &	fileName
	)		[static]

A function to test addDir.

It first sets the directory.

static void casa::ImageExprParse::setNode

(

const LatticeExprNode &

node

)

[inline, static]

Set the static node object (used by the .y file).

Definition at line 283 of file ImageExprParse.h.

References theirNode.

Bool casa::ImageExprParse::tryLatticeNode	(	LatticeExprNode &	node,
		const String &	name
	)		const [private]

Try if the name represent a lattice or image.

Return False if not.

---

Member Data Documentation

Bool casa::ImageExprParse::itsBval [private]

Definition at line 320 of file ImageExprParse.h.

Complex casa::ImageExprParse::itsCval [private]

Definition at line 324 of file ImageExprParse.h.

DComplex casa::ImageExprParse::itsDCval [private]

Definition at line 325 of file ImageExprParse.h.

Double casa::ImageExprParse::itsDval [private]

Definition at line 323 of file ImageExprParse.h.

Float casa::ImageExprParse::itsFval [private]

Definition at line 322 of file ImageExprParse.h.

Int casa::ImageExprParse::itsIval [private]

Definition at line 321 of file ImageExprParse.h.

String casa::ImageExprParse::itsSval [private]

Definition at line 326 of file ImageExprParse.h.

DataType casa::ImageExprParse::itsType [private]

Definition at line 319 of file ImageExprParse.h.

LatticeExprNode casa::ImageExprParse::theirNode [static, private]

Definition at line 317 of file ImageExprParse.h.

Referenced by setNode().

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

• casacore/images/Images/ImageExprParse.h