org.apache.jasper.compiler.tagplugin.TagPluginContext Maven / Gradle / Ivy
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package org.apache.jasper.compiler.tagplugin;
import org.apache.jasper.compiler.ServletWriter;
/**
* This interface allows the plugin author to make inqueries about the
* properties of the current tag, and to use Jasper resources to generate
* direct Java codes in place of tag handler invocations.
*/
public interface TagPluginContext {
/**
* @return true if the body of the tag is scriptless.
*/
boolean isScriptless();
/**
* @param attribute Name of the attribute
* @return true if the attribute is specified in the tag
*/
boolean isAttributeSpecified(String attribute);
/**
* @return An unique temporary variable name that the plugin can use.
*/
String getTemporaryVariableName();
/**
* Generate an import statement
* @param s Name of the import class, '*' allowed.
*/
void generateImport(String s);
/**
* Generate a declaration in the of the generated class. This can be
* used to declare an innter class, a method, or a class variable.
* @param id An unique ID identifying the declaration. It is not
* part of the declaration, and is used to ensure that the
* declaration will only appear once. If this method is
* invoked with the same id more than once in the translation
* unit, only the first declaration will be taken.
* @param text The text of the declaration.
**/
void generateDeclaration(String id, String text);
/**
* Generate Java source codes
*/
void generateJavaSource(String s);
/**
* @return true if the attribute is specified and its value is a
* translation-time constant.
*/
boolean isConstantAttribute(String attribute);
/**
* @return A string that is the value of a constant attribute. Undefined
* if the attribute is not a (translation-time) constant.
* null if the attribute is not specified.
*/
String getConstantAttribute(String attribute);
/**
* Generate codesto evaluate value of a attribute in the custom tag
* The codes is a Java expression.
* NOTE: Currently cannot handle attributes that are fragments.
* @param attribute The specified attribute
*/
void generateAttribute(String attribute);
/*
* Generate codes for the body of the custom tag
*/
void generateBody();
/**
* Abandon optimization for this tag handler, and instruct
* Jasper to generate the tag handler calls, as usual.
* Should be invoked if errors are detected, or when the tag body
* is deemed too compilicated for optimization.
*/
void dontUseTagPlugin();
/**
* Get the PluginContext for the parent of this custom tag. NOTE:
* The operations available for PluginContext so obtained is limited
* to getPluginAttribute and setPluginAttribute, and queries (e.g.
* isScriptless(). There should be no calls to generate*().
* @return The pluginContext for the parent node.
* null if the parent is not a custom tag, or if the pluginConxt
* if not available (because useTagPlugin is false, e.g).
*/
TagPluginContext getParentContext();
/**
* Associate the attribute with a value in the current tagplugin context.
* The plugin attributes can be used for communication among tags that
* must work together as a group. See for an example.
*/
void setPluginAttribute(String attr, Object value);
/**
* Get the value of an attribute in the current tagplugin context.
*/
Object getPluginAttribute(String attr);
}