# Class Symbols

Object
Symbols

All Implemented Interfaces:
  `Serializable`, `Cloneable`, `Localized`

public class Symbols extends Object implements Localized, Cloneable, Serializable
The set of symbols to use for Well Known Text (WKT) parsing and formatting. The two constants defined in this class, namely `SQUARE_BRACKETS` and `CURLY_BRACKETS`, define the symbols for ISO 19162 compliant WKT formatting. Their properties are:

Standard WKT symbols
WKT aspect | Standard value | Comment
--- | --- | ---
Locale for number format: | `Locale.ROOT` |
Bracket symbols: | `[`…`]` or `(`…`)` | Note: the `[…]` brackets are common in referencing WKT, while the `(…)` brackets are common in geometry WKT.
Quote symbols: | `"`…`"` | Note: Apache SIS accepts also `“…”` quotes for more readable `String` literals in Java code, but this is non-standard.
Sequence symbols: | `{`…`}` |
Separator: | `,` |

Users can create their own `Symbols` instance for parsing or formatting a WKT with different symbols.

Since:
  0.4
See Also:
  - `WKTFormat​.getSymbols()`
  - `WKTFormat​.setSymbols(Symbols)`
  - Serialized Form

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final Symbols`
  `CURLY_BRACKETS`
  A set of symbols with values between parentheses, like `DATUM("WGS84")`.
  `static final Symbols`
  `SQUARE_BRACKETS`
  A set of symbols with values between square brackets, like `DATUM["WGS84"]`.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Symbols(Symbols symbols)`
  Creates a new set of WKT symbols initialized to a copy of the given symbols.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Symbols`
  `clone()`
  Returns a clone of this `Symbols`.
  `boolean`
  `containsElement(CharSequence wkt, String element)`
  Returns `true` if the given WKT contains at least one instance of the given element.
  `boolean`
  `equals(Object other)`
  Compares this `Symbols` with the given object for equality.
  `final int`
  `getCloseSequence()`
  Returns the character used for closing a sequence of values.
  `final int`
  `getClosingBracket(int index)`
  Returns the closing bracket character at the given index.
  `final int`
  `getClosingQuote(int index)`
  Returns the closing quote character at the given index.
  `static Symbols`
  `getDefault()`
  Returns the default set of symbols.
  `final Locale`
  `getLocale()`
  Returns the locale for formatting dates and numbers.
  `final int`
  `getNumPairedBrackets()`
  Returns the number of paired brackets.
  `final int`
  `getNumPairedQuotes()`
  Returns the number of paired quotes.
  `final int`
  `getOpeningBracket(int index)`
  Returns the opening bracket character at the given index.
  `final int`
  `getOpeningQuote(int index)`
  Returns the opening quote character at the given index.
  `final int`
  `getOpenSequence()`
  Returns the character used for opening a sequence of values.
  `final String`
  `getSeparator()`
  Returns the string used as a separator in a list of values.
  `int`
  `hashCode()`
  Returns a hash code value for this object.
  `void`
  `setLocale(Locale locale)`
  Sets the locale of decimal format symbols or other symbols.
  `void`
  `setPairedBrackets(String preferred, String... alternatives)`
  Sets the opening and closing brackets to the given pairs.
  `void`
  `setPairedQuotes(String preferred, String... alternatives)`
  Sets the opening and closing quotes to the given pairs.
  `void`
  `setSeparator(String separator)`
  Sets the string to use as a separator in a list of values.
  `void`
  `setSequenceBrackets(int openSequence, int closeSequence)`
  Sets the characters used for opening and closing a sequence of values.

  ### Methods inherited from class Object

  `finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### SQUARE_BRACKETS

    public static final Symbols SQUARE_BRACKETS
    A set of symbols with values between square brackets, like `DATUM["WGS84"]`. This instance defines:
    - `Locale​.ROOT` for decimal format symbols.
    - Square brackets by default, as in `DATUM["WGS84"]`, but accepting also curly brackets as in `DATUM("WGS84")`. Both are legal WKT.
    - English quotation mark (`'"'`) by default, but accepting also “…” quotes for more readable `String` constants in Java code.
    - Coma separator followed by a space (`", "`).
    This is the most frequently used WKT format for referencing objects.

  - ### CURLY_BRACKETS

    public static final Symbols CURLY_BRACKETS
    A set of symbols with values between parentheses, like `DATUM("WGS84")`. This instance is identical to `SQUARE_BRACKETS` except that the default brackets are the curly ones instead of the square ones (but both are still accepted at parsing time).

    This format is rare with referencing objects but common with geometry objects.

- ## Constructor Details

  - ### Symbols

    public Symbols(Symbols symbols)
    Creates a new set of WKT symbols initialized to a copy of the given symbols.
    Parameters:
      `symbols` - the symbols to copy.

- ## Method Details

  - ### getDefault

    public static Symbols getDefault()
    Returns the default set of symbols. This is currently set to `SQUARE_BRACKETS`.
    Returns:
      the default set of symbols.

  - ### getLocale

    public final Locale getLocale()
    Returns the locale for formatting dates and numbers. The default value is `Locale​.ROOT`.

    #### Relationship between `Symbols` locale and `WKTFormat` locale

    The `WKTFormat​.getLocale(Locale​.DISPLAY)` property specifies the language to use when formatting `InternationalString` instances and can be set to any value. On the contrary, the `Locale` property of this `Symbols` class controls the decimal format symbols and is very rarely set to another locale than `Locale​.ROOT`.
    Specified by:
      `getLocale` in interface `Localized`
    Returns:
      the locale for dates and numbers.
    See Also:
      - `WKTFormat​.getLocale(Locale​.Category)`

  - ### setLocale

    public void setLocale(Locale locale)
    Sets the locale of decimal format symbols or other symbols. Note that any non-English locale is likely to produce WKT that do not conform to ISO 19162. Such WKT can be used for human reading, but not for data export.
    Parameters:
      `locale` - the new symbols locale.
    Throws:
      `UnsupportedOperationException` - if this `Symbols` instance is immutable.

  - ### getNumPairedBrackets

    public final int getNumPairedBrackets()
    Returns the number of paired brackets. For example if the WKT parser accepts both the `[…]` and `(…)` bracket pairs, then this method returns 2.
    Returns:
      the number of bracket pairs.
    See Also:
      - `getOpeningBracket(int)`
      - `getClosingBracket(int)`

  - ### getOpeningBracket

    public final int getOpeningBracket(int index)
    Returns the opening bracket character at the given index. Index 0 stands for the default bracket used at formatting time. All other index are for optional brackets accepted at parsing time.
    Parameters:
      `index` - index of the opening bracket to get, from 0 to `getNumPairedBrackets()` exclusive.
    Returns:
      the opening bracket at the given index, as a Unicode code point.
    Throws:
      `IndexOutOfBoundsException` - if the given index is out of bounds.

  - ### getClosingBracket

    public final int getClosingBracket(int index)
    Returns the closing bracket character at the given index. Index 0 stands for the default bracket used at formatting time. All other index are for optional brackets accepted at parsing time.
    Parameters:
      `index` - index of the closing bracket to get, from 0 to `getNumPairedBrackets()` exclusive.
    Returns:
      the closing bracket at the given index, as a Unicode code point.
    Throws:
      `IndexOutOfBoundsException` - if the given index is out of bounds.

  - ### setPairedBrackets

    public void setPairedBrackets(String preferred, String... alternatives)
    Sets the opening and closing brackets to the given pairs. Each string shall contain exactly two code points (usually two characters). The first code point is taken as the opening bracket, and the second code point as the closing bracket.

    #### Example

    The following code will instruct the WKT formatter to use the (…) pair of brackets at formatting time, but still accept the more common […] pair of brackets at parsing time:

        symbols.setPairedBrackets("()", "[]");

    Parameters:
      `preferred` - the preferred pair of opening and closing quotes, used at formatting time.
      `alternatives` - alternative pairs of opening and closing quotes accepted at parsing time.
    Throws:
      `UnsupportedOperationException` - if this `Symbols` instance is immutable.

  - ### getNumPairedQuotes

    public final int getNumPairedQuotes()
    Returns the number of paired quotes. For example if the WKT parser accepts both the `"…"` and `“…”` quote pairs, then this method returns 2.
    Returns:
      the number of quote pairs.
    See Also:
      - `getOpeningQuote(int)`
      - `getClosingQuote(int)`

  - ### getOpeningQuote

    public final int getOpeningQuote(int index)
    Returns the opening quote character at the given index. Index 0 stands for the default quote used at formatting time, which is usually `'"'`. All other index are for optional quotes accepted at parsing time.
    Parameters:
      `index` - index of the opening quote to get, from 0 to `getNumPairedQuotes()` exclusive.
    Returns:
      the opening quote at the given index, as a Unicode code point.
    Throws:
      `IndexOutOfBoundsException` - if the given index is out of bounds.

  - ### getClosingQuote

    public final int getClosingQuote(int index)
    Returns the closing quote character at the given index. Index 0 stands for the default quote used at formatting time, which is usually `'"'`. All other index are for optional quotes accepted at parsing time.
    Parameters:
      `index` - index of the closing quote to get, from 0 to `getNumPairedQuotes()` exclusive.
    Returns:
      the closing quote at the given index, as a Unicode code point.
    Throws:
      `IndexOutOfBoundsException` - if the given index is out of bounds.

  - ### setPairedQuotes

    public void setPairedQuotes(String preferred, String... alternatives)
    Sets the opening and closing quotes to the given pairs. Each string shall contain exactly two code points (usually two characters). The first code point is taken as the opening quote, and the second code point as the closing quote.

    #### Example

    The following code will instruct the WKT formatter to use the prettier “…” quotation marks at formatting time (especially useful for `String` constants in Java code), but still accept the standard "…" quotation marks at parsing time:

        symbols.setPairedQuotes("“”", "\"\"");

    Parameters:
      `preferred` - the preferred pair of opening and closing quotes, used at formatting time.
      `alternatives` - alternative pairs of opening and closing quotes accepted at parsing time.
    Throws:
      `UnsupportedOperationException` - if this `Symbols` instance is immutable.

  - ### getOpenSequence

    public final int getOpenSequence()
    Returns the character used for opening a sequence of values. This is usually `'{'`.
    Returns:
      the character used for opening a sequence of values, as a Unicode code point.

  - ### getCloseSequence

    public final int getCloseSequence()
    Returns the character used for closing a sequence of values. This is usually `'}'`.
    Returns:
      the character used for closing a sequence of values, as a Unicode code point.

  - ### setSequenceBrackets

    public void setSequenceBrackets(int openSequence, int closeSequence)
    Sets the characters used for opening and closing a sequence of values.
    Parameters:
      `openSequence` - the character for opening a sequence of values, as a Unicode code point.
      `closeSequence` - the character for closing a sequence of values, as a Unicode code point.
    Throws:
      `UnsupportedOperationException` - if this `Symbols` instance is immutable.

  - ### getSeparator

    public final String getSeparator()
    Returns the string used as a separator in a list of values. This is usually `", "`, but may be different if a non-English locale is used for formatting numbers.
    Returns:
      the string used as a separator in a list of values.

  - ### setSeparator

    public void setSeparator(String separator)
    Sets the string to use as a separator in a list of values. The given string will be used "as-is" at formatting time, but leading and trailing spaces will be ignored at parsing time.
    Parameters:
      `separator` - the new string to use as a separator in a list of values.
    Throws:
      `UnsupportedOperationException` - if this `Symbols` instance is immutable.

  - ### containsElement

    public boolean containsElement(CharSequence wkt, String element)
    Returns `true` if the given WKT contains at least one instance of the given element. Invoking this method is equivalent to invoking `String​.contains(CharSequence)` except for the following:
    - The search is case-insensitive.
    - Characters between opening quotes and closing quotes are ignored.
    - The element found in the given WKT cannot be preceded by other Unicode identifier characters.
    - The element found in the given WKT must be followed, ignoring space, by an opening bracket.
    The purpose of this method is to guess some characteristics about the encoded object without the cost of a full WKT parsing.

    #### Example

    `containsElement(wkt, "AXIS")` returns `true` if the given WKT contains at least one instance of the `AXIS[…]` element, ignoring case.
    Parameters:
      `wkt` - the WKT to inspect.
      `element` - the element to search for.
    Returns:
      `true` if the given WKT contains at least one instance of the given element.

  - ### clone

    public Symbols clone()
    Returns a clone of this `Symbols`. The returned instance is modifiable (i.e. setter methods will not throw `UnsupportedOperationException`).
    Overrides:
      `clone` in class `Object`
    Returns:
      a modifiable clone of this `Symbols`.

  - ### equals

    public boolean equals(Object other)
    Compares this `Symbols` with the given object for equality.
    Overrides:
      `equals` in class `Object`
    Parameters:
      `other` - the object to compare with this `Symbols`.
    Returns:
      `true` if both objects are equal.

  - ### hashCode

    public int hashCode()
    Returns a hash code value for this object.
    Overrides:
      `hashCode` in class `Object`
    Returns:
      a hash code value.