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## org.apache.poi.ss.formula.ptg
Class Ptg

    java.lang.Object
      org.apache.poi.ss.formula.ptg.Ptg

Direct Known Subclasses:
  ArrayPtg, ControlPtg, OperandPtg, OperationPtg, ScalarConstantPtg, UnknownPtg

    public abstract class Ptg

extends java.lang.Object

`Ptg` represents a syntactic token in a formula. 'PTG' is an acronym for 'parse thing'. Originally, the name referred to the single byte identifier at the start of the token, but in POI, `Ptg` encapsulates the whole formula token (initial byte + value data).

`Ptg`s are logically arranged in a tree representing the structure of the parsed formula. However, in BIFF files `Ptg`s are written/read in Reverse-Polish Notation order. The RPN ordering also simplifies formula evaluation logic, so POI mostly accesses `Ptg`s in the same way.

Author:
  andy, avik, Jason Height (jheight at chariot dot net dot au)

Field Summary
`static byte` | `CLASS_ARRAY`
`static byte` | `CLASS_REF`
`static byte` | `CLASS_VALUE`
`static Ptg[]` | `EMPTY_PTG_ARRAY`

Constructor Summary
`Ptg()`

Method Summary
`static Ptg` | `createPtg(LittleEndianInput in)`
`static boolean` | `doesFormulaReferToDeletedCell(Ptg[] ptgs)`
`abstract byte` | `getDefaultOperandClass()`
`static int` | `getEncodedSize(Ptg[] ptgs)` This method will return the same result as `getEncodedSizeWithoutArrayData(Ptg[])` if there are no array tokens present.
`static int` | `getEncodedSizeWithoutArrayData(Ptg[] ptgs)` Used to calculate value that should be encoded at the start of the encoded Ptg token array;
`byte` | `getPtgClass()`
`char` | `getRVAType()` Debug / diagnostic method to get this token's 'operand class' type.
`abstract int` | `getSize()`
`abstract boolean` | `isBaseToken()`
`static Ptg[]` | `readTokens(int size, LittleEndianInput in)` Reads `size` bytes of the input stream, to create an array of `Ptg`s.
`static int` | `serializePtgs(Ptg[] ptgs, byte[] array, int offset)` Writes the ptgs to the data buffer, starting at the specified offset.
`void` | `setClass(byte thePtgClass)`
`abstract java.lang.String` | `toFormulaString()` return a string representation of this token alone
`java.lang.String` | `toString()` Overridden toString method to ensure object hash is not printed.
`abstract void` | `write(LittleEndianOutput out)`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Field Detail

### EMPTY_PTG_ARRAY

    public static final Ptg[] EMPTY_PTG_ARRAY

### CLASS_REF

    public static final byte CLASS_REF

See Also:
  Constant Field Values

### CLASS_VALUE

    public static final byte CLASS_VALUE

See Also:
  Constant Field Values

### CLASS_ARRAY

    public static final byte CLASS_ARRAY

See Also:
  Constant Field Values

Constructor Detail

### Ptg

    public Ptg()

Method Detail

### readTokens

    public static Ptg[] readTokens(int size,
                                   LittleEndianInput in)

  Reads `size` bytes of the input stream, to create an array of `Ptg`s. Extra data (beyond `size`) may be read if and `ArrayPtg`s are present.

### createPtg

    public static Ptg createPtg(LittleEndianInput in)

### getEncodedSize

    public static int getEncodedSize(Ptg[] ptgs)

  This method will return the same result as `getEncodedSizeWithoutArrayData(Ptg[])` if there are no array tokens present.

  Returns:
    the full size taken to encode the specified `Ptg`s

### getEncodedSizeWithoutArrayData

    public static int getEncodedSizeWithoutArrayData(Ptg[] ptgs)

  Used to calculate value that should be encoded at the start of the encoded Ptg token array;

  Returns:
    the size of the encoded Ptg tokens not including any trailing array data.

### serializePtgs

    public static int serializePtgs(Ptg[] ptgs,
                                    byte[] array,
                                    int offset)

  Writes the ptgs to the data buffer, starting at the specified offset.
  The 2 byte encode length field is not written by this method.

  Returns:
    number of bytes written

### getSize

    public abstract int getSize()

  Returns:
    the encoded length of this Ptg, including the initial Ptg type identifier byte.

### write

    public abstract void write(LittleEndianOutput out)

### toFormulaString

    public abstract java.lang.String toFormulaString()

  return a string representation of this token alone

### toString

    public java.lang.String toString()

  Overridden toString method to ensure object hash is not printed. This helps get rid of gratuitous diffs when comparing two dumps Subclasses may output more relevant information by overriding this method

  Overrides:
    `toString` in class `java.lang.Object`

### setClass

    public final void setClass(byte thePtgClass)

### getPtgClass

    public final byte getPtgClass()

  Returns:
    the 'operand class' (REF/VALUE/ARRAY) for this Ptg

### getRVAType

    public final char getRVAType()

  Debug / diagnostic method to get this token's 'operand class' type.

  Returns:
    'R' for 'reference', 'V' for 'value', 'A' for 'array' and '.' for base tokens

### getDefaultOperandClass

    public abstract byte getDefaultOperandClass()

### isBaseToken

    public abstract boolean isBaseToken()

  Returns:
    `false` if this token is classified as 'reference', 'value', or 'array'

### doesFormulaReferToDeletedCell

    public static boolean doesFormulaReferToDeletedCell(Ptg[] ptgs)

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