Wednesday, June 04, 2014

GTViewer Expression Syntax

The following reference is for the Expression Syntax used by various GTI products.   This post will provide an easy to find reference without having to remember which document it is in.  

The expression syntax is used by GTViewer's Dynamic Graphics, Feature Tooltips, Custom Attribute Info Tabs, Link Definitions, and Where Am I.    GTViewer and GTVx also provide set of methods to directly access the Expression Evaluator:  ExpStateReset, ExpStateAddValue, ExpStateGetValue, ExpStateGetValueType, ExpStateGetInfo, ExpStateLoadElementData, ExpStateLoadTabularData, ExpValidate, and ExpEvaluate. 

GTWeb also supports the Custom Attribute Tabs and Where Am I functionality.

*** NOTE: Some of the formatting of the Less Than and Greater Than signs didn't come through on this post.  I will work on getting that fixed.

GTViewer Expression Syntax

Literals. 3
  • Integer Literals
  • Double Literals
  • String Literals
Arithmetic Operators
  • Unary Operators:  + , -
  • Binary Operators:  /, *, +, -
Grouping Operators
  • Parentheses
Comparison Operators
  • Equality Operators:  =,  ==, <>, !=
  • Relational Operators:  <,  >,  <=,  >=
  • Special Comparison Operators: LIKE, IN
Logical Operators
  • Logical AND
  • Logical OR
  • Logical NOT and !
Type Cast Functions
  • Integer Cast Functions:  ToInt, CInt
  • Double Cast Functions: ToDouble, CDbl
  • String Cast Functions: ToString, CStr
String Functions
  • Trim Functions: LTrim, RTrim, Trim
  • Case Functions: Upper, Lower
  • String Length Function: Length
  • String Concatenation Function: Concat
  • String Extraction Function: Substr
  • String Replacement Function: Replace
  • String Padding Functions:  RPad, LPad
  • String Search Function: Instr
  • String From ASCII Code Function: CHR
  • Number Formatting Function: Format
  • String Formatting Function:  Pretty
Miscellaneous Functions
  • IF Function:  IFFUNCT
Constants
Variables

. 15
Special Variables. 17


Integer Literals
·         Integer Literals are 32 bit signed Integer values (-2,147,483,648 through 2,147,483,647).

Example
123
0
1024


Double Literals
·         Double Literals are 64 bit double values (4.94065645841246544E-324 through 1.79769313486231570E+308).

Example
0.0
123.456
3.14159


String Literals
·         A String Literal must be enclosed in single quotes (' ') or double quotes (" ").

Example
'a'
"a"
'abc'
"abc"




Arithmetic Operators

Unary Operators:  + , -
·         The unary + operator will make the operand positive.

Example
Evaluates To
+1 
1
+1 + 1 
2
+1++1 
2

·         The unary – operator will negate the operand.

Example
Evaluates To
-2
-2
1 + -2
-1
1 - -1
2


Binary Operators:  /, *, +, -

·         The / operator will divide the left operand by the right operand.

Example
Evaluates To
6 / 3
2.000000
3 / 2
1.500000
5 / 0 
**Error**

·         The * operator will multiply the left operand by the right operand.

Example
Evaluates To
6 * 3
18
3 * 0.5
1.500000
5 * 0 
0

·         The + operator will add the left and right operands.

Example
Evaluates To
6 + 3
9
3 + 0.5
3.500000
5 + 0 
5

·         The – operator will subtract the right operand from the left operand.

Example
Evaluates To
6 - 3
3
3 - 0.5
2.500000
5 - 0 
5



Grouping Operators 

Parentheses
·         The Parentheses operators can be used to group parts of an expression together so that their order of execution can be controlled.   Grouped parts of an expression are evaluated inside out.

Example
Evaluates To
(1)
1
(1 + 2) * (3 + 4)
21
(1 < 2) and (4 < 3 or 1>2 or 3>1)
1



Comparison Operators

Equality Operators:  =,  ==, <>, !=
·         Both the = and == operators can be used for equality comparisons.   They will return 1 (True) if the left and right operands are equal; otherwise, they will return 0 (False).
Example
Evaluates To
2 = 1+1
1
3 = 1 + 1
0
2 == 1 + 1
1
3 == 1 + 1
0
'abc' = 'def'
0

·         Both the <> and != operators can be used for inequality comparisons.  They will return 0 (False) if the left and right operands are equal; otherwise, they will return 1 (True).

Example
Evaluates To
2 <> 1+1
0
3 <> 1 + 1
1
2 != 1 + 1
0
3 != 1 + 1
1
'abc' <> 'def'
1


Relational Operators:  <, >,  <=,  >=
·         The < operator will return 1 (True) if the left operand is less than the right operand; otherwise, it will return 0 (False).

Example
Evaluates To
123 < 456
1
456 < 123
0
123 < 123
0
'abc' < 'def'
1


·         The <= operator will return 1 (True) if the left operand is less than or equal to the right operand; otherwise, it will return 0 (False).

Example
Evaluates To
123 <= 456
1
123 <= 123
1

·         The > operator will return 1 (True) if the left operand is greater than the right operand; otherwise, it will return 0 (False).

Example
Evaluates To
123 > 456
0
456 > 123
1
123 > 123
0
'abc' > 'def'
0

·         The >= operator will return 1 (True) if the left operand is greater than or equal to the right operand; otherwise, it will return 0 (False).

Example
Evaluates To
456 >= 123
1
123 >= 123
1

Special Comparison Operators: LIKE, IN
·         The LIKE operator will compare the left String operand to a pattern defined in the right String operand.   The following patterns are allowed where 'xxx' is a string and the % is the accepted wildcard character:  Begins With ('xxx%'), Ends With ('%xxx'), and Contains ('%xxx%).

Example
Evaluates To
'abc' like 'abc'
1
'abcdef' like 'abc%'
1
'abcdef' like '%def'
1
'abcdef' like '%cd%'
1
'abc' like '%'
1
'abc' like '%bcd'
0
'abcdef' like '%defg%'
0
'abcdef' like '%abc%'
1
'abcdef' like '%def%'
1

·         The IN operator will compare the left operand to the parenthesis enclosed list of expressions in the right operand.  If the left operand matches an item in the list, 1 (True) is returned; otherwise, 0 (False) is returned.   The list of expressions on the right must evaluate to a type compatible with the left operand’s type (Numbers to Numbers, Strings to String).

Example
Evaluates To
123 IN (100,110,120,130)
0
120 IN (100,120,130,140)
1
'D' IN ('A', 'B', 'C', 'D', 'E')
1




Logical Operators

Logical AND
·         The AND operator will return 1 (True) if the left and right operands are both True (evaluate to a non-zero value).  If one or both of the operands are False (evaluate to 0), then 0 (False) is returned.

Example
Evaluates To
1 and 1
1
1 and 0
0
0 and 1
0
0 and 0
0
True and True
1
True and False
0
False and True
0
False and False
0

Logical OR
·         The OR operator will return 1 (True) if either the left or the right operand is True (evaluates to non-zero value).   If both operands are False (evaluate to 0), then 0 (False) is returned.

Example
Evaluates To
1 or 0
1
0 or 1
1
1 or 1
1
0 or 0
0
True or False
1
False or True
1
True or True
1
False or False
0

Logical NOT and !
·         The NOT and ! operators will return 0 (False) if the following operand is True (evaluates to a non-zero value) and will return 1 (True) if the operand is False (evaluates to a 0).

Example
Evaluates To
Not 1
0
Not 0
1
!1
0
!0
1
Not True
0
Not False
1
!True
0
!False
1

Type Cast Functions

The Type Cast Functions are used to convert the type of an expression to another type.  For example, Integer and Double values can be converted to Strings, and Strings can be converted to Integer or Double values.
  • Type Cast Function syntax: 
    • ToInt( ) as Integer
    • CInt( ) as Integer
    • ToDouble( )  as Double
    • CDbl( ) as Double
    • ToString( ) as String
    • CStr( ) as String

Integer Cast Functions:  ToInt, CInt
  • The ToInt and CInt functions will cast a Double or String expression to an Integer Value.  If a String cannot be converted, it will return 0.   The Decimal value for Double values will be truncated.

Example
Evaluates To
ToInt( '123456')
123456
CInt( 1234.56 )
1234


Double Cast Functions: ToDouble, CDbl
  • ToDouble and CDbl will cast an Integer or String expression to a Double value.   If a String cannot be converted, it will return a 0.0.

Example
Evaluates To
ToDouble( '123.456' )
123.456000
CDbl( 123 )
123.000000


String Cast Functions: ToString, CStr
·         ToString and CStr will cast a Double or Integer expression to a String Value.

Example
Evaluates To
ToString( 1 + 2 + 3 )
'6'
CStr( 1 + 2 + 3 )
'6'




String Functions

Trim Functions: LTrim, RTrim, Trim
·         The LTrim function returns the String value specified in the first parameter with no leading spaces.

§   LTrim( str as String ) as String

Example
Evaluates To
LTrim('   abc   ')
'abc   '

·         The RTrim function returns the String value specified in the first parameter with no trailing spaces.

§   RTrim( str as String ) as String

Example
Evaluates To
RTrim('   abc   ')
'   abc'

·         The Trim function the String value specified in the first parameter with no leading or trailing spaces.

§   Trim( str as String ) as String

Example
Evaluates To
Trim('   abc   ')
'abc'

Case Functions: Upper, Lower

·         The Upper function returns the String value specified in the first parameter in all upper case.

§   Upper( str as String ) as String

Example
Evaluates To
Upper('abc')
'ABC'

·         The Lower function returns the String value specified in the first parameter in all lower case.

§   Lower( str as String ) as String

Example
Evaluates To
Lower('ABC')
'abc'



String Length Function: Length
·         The Length function returns an Integer value specifying the number of characters in the String value specified in the first parameter.

§   Length( str as String ) as Integer

Example
Evaluates To
Length('abc')
3
Length('')
0


String Concatenation Function: Concat
·         The Concat function returns a String value that is the concatenation all String values specified as parameters.   There must be from 2 to 10 String values provided as parameters.

§   Concat( str1 as String, str2 as String) as String
§   Concat( str1 as String, str2 as String, …, str_N as String ) as String

Example
Evaluates To
Concat('abc', 'def')
'abcdef'
Concat('abc', 'def', 'ghi')
'abcdefghi'
Concat('abc', 'def', 'ghi', 'jkl')
'abcdefghijkl'


String Extraction Function: Substr
·         The Substr function returns a String value containing a substring of the String value provided in the first parameter.  The second parameter is an Integer value specifying the zero based starting position of the substring.  A third, optional Integer parameter can be used to specify the length of the substring; if no length is specified, the substring will go from the starting position to the end of the string.

§   Substr( str as String, startPos as Integer ) as String
§   SubStr( str as String, startPos as Integer, length as Integer ) as String

Example
Evaluates To
Substr('abcdef',3)
'def'
Substr('abcdef',2,2)
'cd'


String Replacement Function: Replace
·         The Replace function returns a new String value created by taking the String value specified in the first parameter and replacing all of its occurrences of the String specified in the second parameter with the String value specified in the third parameter.  The third parameter is optional; omitting it will remove all occurrences of the second parameter from the first.

§   Replace( str as String, oldValue as String ) as String
§  Replace ( str as String, oldValue as String, newValue as String) as String


Example
Evaluates To
Replace('abcdef','bcde')
'af'
Replace('abcdef','bcde','*')
'a*f'


String Padding Functions:  RPad, LPad
·         The RPad function returns a String value where the first parameter String value is padded on the right side with the number of spaces needed to make the String contain the number of characters specified by the second parameter.  A third, optional parameter can specify the padding String value.

§   RPad( str as String, count as Integer ) as String
§   RPad( str as String, count as Integer, padStr as String ) as String


Example
Evaluates To
RPad('abc',6)
'abc   '
RPad('abc',6,'~')
'abc~~~'

·          The LPad function returns a String value where the first parameter String value is padded on the left side with the number of spaces need to make the String contain the number of character specified by the second parameter.  A third, optional parameter can specify the padding String value.

§   LPad( str as String, count as Integer) as String
§   LPad( str as String, count as Integer, padStr as String) as String

Example
Evaluates To
LPad('abc',5)
'  abc'
LPad('abc',5,'*')
'**abc'



String Search Function: Instr
·         The Instr function returns the zero-based index position in the first parameter String value of the second parameter String value.  A third, optional parameter can be used to specify a zero-based search starting position; 0 is used as the starting position if the third parameter is not specified.  If the second parameter String is not found in the first, the function will return -1.

§   Instr( str as String, searchStr as String ) as String
§   Instr( str as String, searchStr as String, startPos as Integer ) as String

Example
Evaluates To
Instr('abcdefghij','fgh')
5
Instr('abcdefghij','jkl')
-1
Instr('abcdabcdabcd','d',8)
11
Instr('abcdabcdabcd','a',9)
-1


String From ASCII Code Function: CHR

  • The CHR function returns a String value containing the ASCII character for the specified integer value.
§   CHR( val as INTEGER ) as String

Example
Evaluates To
CHR(65)
'A'
CHR(97)
'a'
CHR(48)
'0'


Number Formatting Function: Format
·         The Format function returns a String value of a Double value specified in the first parameter.  The second parameter is an Integer value specifying the width of the string that will be created.  The third, optional parameter can be used to specify the zero-based number of the digit that will be shown to the right of the decimal point.

§   Format( value as Double, width as Integer ) as String
§   Format( value as Double, width as Integer, prec as Integer ) as String

Example
Evaluates To
Format(12.452, 6,2)
' 12.45'
Format(12.456, 6,2)
' 12.46'
Format(12.456, 6,4)
'12.4560'
Format(12.456, 6)
'    12'




String Formatting Function:  Pretty
  • The Pretty function returns a String value that has been formatted according to a specify rule.  This first parameter specifies a string to format.  The second optional parameter is the mode and can be 0, 1, or 2.  If the mode is not set, it will default to 0.  The modes are listed below:
·         Mode 0 – Capitalize the first letter of each word in the string and make the rest of the characters lower case.
·         Mode 1 – Replace all Underscores (_) with spaces.
·         Mode 2 – Combination of modes 0 and 1.

§   Pretty( value as String ) as String
§   Pretty( value as String, mode as Integer ) as String

Example
Evaluates To
Format('THIS_IS_A_TEST')
'This_Is_A_Test'
Format('THIS_IS_A_TEST',0)
'This_Is_A_Test'
Format('THIS_IS_A_TEST',1)
'THIS IS A TEST'
Format('THIS_IS_A_TEST',2)
'This Is A Test'




Miscellaneous Functions

IF Function:  IFFUNCT
  • The IFFUNCT function will evaluate the expression specified in the first parameter.  If the expression is True (non-zero), the second parameter expression is evaluated and returned; otherwise, the third parameter expression is evaluated and returned.   The second parameter determines the return type.

§   IfFunct( , , ) as

Example
Evaluates To
IfFunct( 1, 'a','b')
'a'
IfFunct( 0, 'a','b')
'b'
IfFunct( 1, 2, 3)
2
IfFunct( 0, 2, 3)
3


Constants

           Constants:  TRUE, FALSE, CRLF

·         The TRUE constant is an Integer value that will always evaluate to 1.
·         The FALSE constant is an Integer value that will always evaluate to 0.
·         The CRLF constant is a String value that will always evaluate to a Carriage Return-Linefeed character (\n).

Example
Evaluates To
True
1
False
0
CRLF
'\n'


Variables

Variables:   , []

o   Variables can be of the INTEGER, DOUBLE, or STRING type.
o   Variable Name can be any Alphabetical character followed by zero or more Alphanumeric characters, or an Under Score (_).

Example
A
Var1
Var_1

o   For variable names that don’t meet the above criteria, Complex Name can be used.  They can contain any Letter, Number, or Symbol except square brackets ( [ , ] ), single quotes ( ' ), or double quotes ( " ).  The Complex Name must be enclosed in square brackets.

Example
[a]
[Pole.Material]
[Pole Material]




Special Variables

There are currently two special variables that can be used with the Dynamic Graphics’ Criteria Expression and Label Expression.  These values are driven by the feature’s geometry.

·         [GTI_GTI.Length] will be set to the linear length of Linear and Shape features.  Its value will be returned as a String type, so it must be cast as a Double (with ToDouble) to be used as a numeric value.   The units will always be master units. 

·         [GTI_DG.Area] will be set to a Shape features area.  Its value will be returned as a String type, so it must be cast as a Double (with ToDouble) to be used as a numeric value.  The units will always be square master units.



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