org.openpdf.renderer.function.postscript.operation.Copy Maven / Gradle / Ivy
Show all versions of openpdf-renderer Show documentation
package org.openpdf.renderer.function.postscript.operation;
import java.util.Stack;
final class Copy implements PostScriptOperation {
@Override
/**
* any1 ... anyn n copy any1 ... anyn any1 ... anyn
* array1 array2 copy subarray2
* string1 string2 copy substring2
*
* performs two entirely different functions, depending on the
* type of the topmost operand.
* In the first form, where the top element on the operand
* stack is a nonnegative integer n, copy pops n from the
* stack and duplicates the top n elements on the stack
* as shown above. This form of copy operates only on the
* objects themselves, not on the values of composite objects.
*
* Examples
* (a) (b) (c) 2 copy Þ (a) (b) (c) (b) (c)
* (a) (b) (c) 0 copy Þ (a) (b) (c)
*
* In the other forms, copy copies all the elements of the
* first composite object into the second. The composite
* object operands must be of the same type, except that
* a packed array can be copied into an array (and only into
* an array—copy cannot copy into packed arrays, because
* they are read-only). This form of copy copies the value of
* a composite object. This is quite different from dup and
* other operators that copy only the objects themselves
* (see Section 3.3.1, "Simple and Composite Objects").
* However, copy performs only one level of copying.
* It does not apply recursively to elements that are
* themselves composite objects; instead, the values
* of those elements become shared. In the case of arrays or
* strings, the length of the second object must be at least as
* great as the first; copy returns the initial subarray or
* substring of the second operand into which the elements
* were copied. Any remaining elements of array2 or
* string2 are unaffected.
*
* Example:
* /a1 [1 2 3] def
* a1 dup length array copy Þ [1 2 3]
*
* errors: invalidaccess, rangecheck, stackoverflow,
* stackunderflow, typecheck
*/
public void eval(Stack