Postscript Operators 'x','y', and 'z'



xcheck any xcheck bool
tests whether the operand has the executable or literal attribute, returning true if it is executable or false if it is literal. This has nothing to do with the object's access attribute-for example, execute-only.

ERRORS: stackunderflow

SEE ALSO: cvx, cvlit
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xor bool1 bool2 xor bool3
int1 int2 xor int3

If the operands are booleans, xor pushes their logical "exclusive or." If the operands are integers, xor pushes the bitwise "exclusive or" of their binary representations.

% A complete truth table
true true xor -> false
true false xor -> true
false true xor -> true
false false xor -> false
7 3 xor -> 4 12 3 xor -> 15

ERRORS: stackunderflow, typecheck

SEE ALSO: or, and,

not

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xshow string numarray xshow
- string numstring xshow - LEVEL 2

is similar to xyshow. However, for each character shown, xshow extracts only one number from numarray or numstring. It uses that number as the x displacement and the value zero as the y displacement. In all other respects, xshow behaves the same as xyshow.

ERRORS: invalidaccess, invalidfont,

nocurrentpoint, rangecheck,

stackunderflow, typecheck

SEE ALSO: xyshow, show

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xyshow string numarray xyshow - string numstring xyshow - LEVEL 2

paints successive characters of string in a manner similar to show. After painting each character, it extracts two successive numbers from the array numarray or the encoded number string numstring. These two numbers, interpreted in user space, determine the position of the origin of the next character relative to the origin of the character just shown. The first number is the x displacement and the second number is the y displacement. In other words, the two numbers override the character's normal width. If numarray or numstring is exhausted before all the characters of string have been shown, a rangecheck error will occur.

ERRORS: invalidaccess, invalidfont,

nocurrentpoint, rangecheck,

stackunderflow, typecheck

SEE ALSO: xshow, yshow, show

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yield - yield - DPS

suspends the current execution context until all other contexts have had a chance to execute. This should not be used as a synchronization primitive, because there is no way to predict how much execution the other contexts will be able to accomplish. The purpose of yield is to break up long-running computations that might lock out other contexts.

ERRORS: (none)
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yshow string numarray yshow - string numstring yshow - LEVEL 2

is similar to xyshow. However, for each character shown, yshow extracts only one number from numarray or numstring. It uses that number as the y displacement and the value zero as the x displacement. In all other respects, it behaves the same as xyshow.

ERRORS: invalidaccess, invalidfont,

nocurrentpoint, rangecheck,

stackunderflow, typecheck

SEE ALSO: xyshow, show

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