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--- visual3d:documentation:pipeline:expressions:reserved_characters [2024/06/19 12:49] – sgranger
+++ visual3d:documentation:pipeline:expressions:reserved_characters [2025/06/20 19:00] (current) – Cleaned up page. wikisysop
@@ Line 1: / Line 1: @@
-reserved characters in expressions
+====== Reserved Characters ======
-===== contents =====
+Several characters are reserved in the syntax for [[visual3d:documentation:pipeline:expressions:expressions_overview|expressions]]. Because these reserved characters are interpreted by Visual3D's expression parser, a special notation is required to indicated that these characters should be used literally.
+===== Ampersand =====
+<code>AMP = &</code>
-  * [[#amp|1 amp]]
+For example, if the desired pipeline command were as follows:
-  * [[#colon|2 colon]]
-  * [[#semicolon|3 semicolon]]
-  * [[#plus|4 plus]]
-  * [[#fslash|5 fslash]]
-  * [[#space|6 space]]
+<code>
+Select_Active_File
+/FILE_NAME=ALL_FILES
+/QUERY= TAG1 & TAG2
+;
+</code>
-===== amp =====
+If the tags TAG1 and TAG2 exist then all files that have been assigned both tags will be active. If, however, we want to use pipeline parameters in place of the text TAG1 and TAG2, we have a problem because there is no way to stop Visual3D from using the & character to concatenate the text. The solution was to introduce a reserved parameter ::AMP. The following pipeline would result:
-amp = &
+<code>
+Set_Pipeline_Parameter
+/PARAMETER_NAME=A
+/PARAMETER_VALUE=TAG1
+;
-for example, if the desired pipeline command were as follows:
+Set_Pipeline_Parameter
+/PARAMETER_NAME=B
+/PARAMETER_VALUE=TAG2
+;
-**select_active_file**
+Select_Active_File
-/file_name=all_files
+/FILE_NAME=ALL_FILES
-/query= tag1 & tag2
+/QUERY= ::A&::AMP&::B
-**;**
+;
-if the tags tag1 and tag2 exist then all files that have been assigned both tags will be active.
+</code>
-if, however, we want to use pipeline parameters in place of the text tag1 and tag2, we have a problem because there is no way to stop visual3d from using the & character to concatenate the text. the solution was to introduce a reserved parameter ::amp.
+and this would result in Visual3D interpreting the query: /QUERY=TAG1 & TAG2. More examples of using the AMP operator can be found [[visual3d:documentation:pipeline:expressions:example_using_the_amp_operator|here]].
-the following pipeline would result
+===== Colon =====
-set_pipeline_parameter
+<code>COLON = :</code>
-**set_pipeline_parameter**
+The ":" character is used through the pipeline and expression syntax, notably when specify a [[visual3d:documentation:pipeline:expressions:expression_syntax#data_tree_syntax|signal in the data tree]].
-/parameter_name=a
-/parameter_value=tag1
-**;**
-**set_pipeline_parameter**
-/parameter_name=b
-/parameter_value=tag2
-**;**
-**select_active_file**
-**/file_name=all_files**
-**/query= ::a&::amp&::b**
-**;**
-this would result in visual3d interpreting the query
-/query=tag1 & tag2
+===== Semicolon =====
-for more: [[https://www.c-motion.com/v3dwiki/index.php?title=expressions:_examples_of_using_the_amp_operator|examples of using the amp operator]]
-===== colon =====
+<code>SEMICOLON = ;</code>
-colon = :
+The ";" character is parsed to indicate the end of a pipeline command.
-===== semicolon =====
+===== Plus Sign =====
-semicolon = ;
+<code>PLUS = +</code>
-===== plus =====
+The "+" character is parsed to indicate concatenation of list items.
-plus = +
+===== Forward Slash =====
-===== fslash =====
+<code>FSLASH = /</code>
-fslash = /
+The "/" character is parsed to indicate the beginning of a pipeline command parameter.
-===== space =====
+===== Space Character =====
-space=" "
+<code>SPACE=" "</code>
+The parser ignores space characters by default.