Package org.apache.calcite.rex

Class RexLiteral

java.lang.Object
org.apache.calcite.rex.RexNode
org.apache.calcite.rex.RexLiteral
public class RexLiteral extends RexNode
Constant value in a row-expression.

There are several methods for creating literals in RexBuilder: RexBuilder.makeLiteral(boolean) and so forth.

How is the value stored? In that respect, the class is somewhat of a black box. There is a getValue() method which returns the value as an object, but the type of that value is implementation detail, and it is best that your code does not depend upon that knowledge. It is better to use task-oriented methods such as getValue2() and toJavaString(java.lang.Comparable, org.apache.calcite.sql.type.SqlTypeName, org.apache.calcite.rel.type.RelDataType, org.apache.calcite.rex.RexDigestIncludeType).

The allowable types and combinations are:

Allowable types for RexLiteral instances
TypeName Meaning Value type
SqlTypeName.NULL The null value. It has its own special type. null
SqlTypeName.BOOLEAN Boolean, namely TRUE, FALSE or UNKNOWN. Boolean, or null represents the UNKNOWN value
SqlTypeName.DECIMAL Exact number, for example 0, -.5, 12345. BigDecimal
SqlTypeName.DOUBLE Approximate number, for example 6.023E-23. BigDecimal
SqlTypeName.DATE Date, for example DATE '1969-04'29' Calendar; also Calendar (UTC time zone) and Integer (days since POSIX epoch)
SqlTypeName.TIME Time, for example TIME '18:37:42.567' Calendar; also Calendar (UTC time zone) and Integer (milliseconds since midnight)
SqlTypeName.TIMESTAMP Timestamp, for example TIMESTAMP '1969-04-29 18:37:42.567' TimestampString; also Calendar (UTC time zone) and Long (milliseconds since POSIX epoch)
SqlTypeName.INTERVAL_DAY, SqlTypeName.INTERVAL_DAY_HOUR, SqlTypeName.INTERVAL_DAY_MINUTE, SqlTypeName.INTERVAL_DAY_SECOND, SqlTypeName.INTERVAL_HOUR, SqlTypeName.INTERVAL_HOUR_MINUTE, SqlTypeName.INTERVAL_HOUR_SECOND, SqlTypeName.INTERVAL_MINUTE, SqlTypeName.INTERVAL_MINUTE_SECOND, SqlTypeName.INTERVAL_SECOND Interval, for example INTERVAL '4:3:2' HOUR TO SECOND BigDecimal; also Long (milliseconds)
SqlTypeName.INTERVAL_YEAR, SqlTypeName.INTERVAL_YEAR_MONTH, SqlTypeName.INTERVAL_MONTH Interval, for example INTERVAL '2-3' YEAR TO MONTH BigDecimal; also Integer (months)
SqlTypeName.CHAR Character constant, for example 'Hello, world!', '', _N'Bonjour', _ISO-8859-1'It''s superman!' COLLATE SHIFT_JIS$ja_JP$2. These are always CHAR, never VARCHAR. NlsString; also String
SqlTypeName.BINARY Binary constant, for example X'7F34'. (The number of hexits must be even; see above.) These constants are always BINARY, never VARBINARY. ByteBuffer; also byte[]
SqlTypeName.SYMBOL A symbol is a special type used to make parsing easier; it is not part of the SQL standard, and is not exposed to end-users. It is used to hold a flag, such as the LEADING flag in a call to the function TRIM([LEADING|TRAILING|BOTH] chars FROM string). An enum class

  • Method Details

    • computeDigest

      @RequiresNonNull({"typeName","type"}) public final String computeDigest(@UnknownInitialization RexLiteral this, RexDigestIncludeType includeType)
      Returns a string which concisely describes the definition of this rex literal. Two literals are equivalent if and only if their digests are the same.

      The digest does not contain the expression's identity, but does include the identity of children.

      Technically speaking 1:INT differs from 1:FLOAT, so we need data type in the literal's digest, however we want to avoid extra verbosity of the RelNode.getDigest() for readability purposes, so we omit type info in certain cases. For instance, 1:INT becomes 1 (INT is implied by default), however 1:BIGINT always holds the type

      Here's a non-exhaustive list of the "well known cases":

      • Hide "NOT NULL" for not null literals
      • Hide INTEGER, BOOLEAN, SYMBOL, TIME(0), TIMESTAMP(0), DATE(0) types
      • Hide collation when it matches IMPLICIT/COERCIBLE
      • Hide charset when it matches default
      • Hide CHAR(xx) when literal length is equal to the precision of the type. In other words, use 'Bob' instead of 'Bob':CHAR(3)
      • Hide BOOL for AND/OR arguments. In other words, AND(true, null) means null is BOOL.
      • Hide types for literals in simple binary operations (e.g. +, -, *, /, comparison) when type of the other argument is clear. See RexCall.computeDigest(boolean) For instance: =(true. null) means null is BOOL. =($0, null) means the type of null matches the type of $0.
      Parameters:
      includeType - whether the digest should include type or not
      Returns:
      digest

    • valueMatchesType

      public static boolean valueMatchesType(@Nullable Comparable value, SqlTypeName typeName, boolean strict)
      Returns whether a value is appropriate for its type. (We have rules about these things!)

    • strictTypeName

      public static SqlTypeName strictTypeName(RelDataType type)
      Returns the strict literal type for a given type. The rules should keep sync with what RexBuilder.makeLiteral(java.lang.Comparable, org.apache.calcite.rel.type.RelDataType, org.apache.calcite.sql.type.SqlTypeName) defines.

    • validConstant

      public static boolean validConstant(@Nullable Object o, Litmus litmus)
      Returns whether a value is valid as a constant value, using the same criteria as valueMatchesType(java.lang.Comparable, org.apache.calcite.sql.type.SqlTypeName, boolean).

    • printAsJava

      public void printAsJava(PrintWriter pw)
      Prints the value this literal as a Java string constant.

    • fromJdbcString

      public static @PolyNull RexLiteral fromJdbcString(RelDataType type, SqlTypeName typeName, @PolyNull String literal)
      Converts a Jdbc string into a RexLiteral. This method accepts a string, as returned by the Jdbc method ResultSet.getString(), and restores the string into an equivalent RexLiteral. It allows one to use Jdbc strings as a common format for data.

      Returns null if and only if literal is null.

      Parameters:
      type - data type of literal to be read
      typeName - type family of literal
      literal - the (non-SQL encoded) string representation, as returned by the Jdbc call to return a column as a string
      Returns:
      a typed RexLiteral, or null

    • getTypeName

      public SqlTypeName getTypeName()

    • getType

      public RelDataType getType()
      Specified by:
      getType in class RexNode

    • getKind

      public SqlKind getKind()
      Description copied from class: RexNode
      Returns the kind of node this is.
      Overrides:
      getKind in class RexNode
      Returns:
      Node kind, never null

    • isNull

      public boolean isNull()
      Returns whether this literal's value is null.

    • getValue

      @Pure public @Nullable Comparable getValue()
      Returns the value of this literal.

      For backwards compatibility, returns DATE. TIME and TIMESTAMP as a Calendar value in UTC time zone.

    • getValue2

      public @Nullable Object getValue2()
      Returns the value of this literal, in the form that the calculator program builder wants it.

    • getValue3

      public @Nullable Object getValue3()
      Returns the value of this literal, in the form that the rex-to-lix translator wants it.

    • getValue4

      public @Nullable Comparable getValue4()
      Returns the value of this literal, in the form that RexInterpreter wants it.

    • getValueAs

      public <T> @Nullable T getValueAs(Class<T> clazz)
      Returns the value of this literal as an instance of the specified class.

      The following SQL types allow more than one form:

      Called with clazz = Comparable, returns the value in its native form.

      Type Parameters:
      T - Return type
      Parameters:
      clazz - Desired return type
      Returns:
      Value of this literal in the desired type

    • booleanValue

      public static boolean booleanValue(RexNode node)

    • isAlwaysTrue

      public boolean isAlwaysTrue()
      Description copied from class: RexNode
      Returns whether this expression always returns true. (Such as if this expression is equal to the literal TRUE.)
      Overrides:
      isAlwaysTrue in class RexNode

    • isAlwaysFalse

      public boolean isAlwaysFalse()
      Description copied from class: RexNode
      Returns whether this expression always returns false. (Such as if this expression is equal to the literal FALSE.)
      Overrides:
      isAlwaysFalse in class RexNode

    • equals

      public boolean equals(@Nullable Object obj)
      Description copied from class: RexNode

      Every node must implement RexNode.equals(java.lang.Object) based on its content

      Specified by:
      equals in class RexNode

    • hashCode

      public int hashCode()
      Description copied from class: RexNode

      Every node must implement RexNode.hashCode() consistent with RexNode.equals(java.lang.Object)

      Specified by:
      hashCode in class RexNode

    • value

      public static @Nullable Comparable value(RexNode node)

    • intValue

      public static int intValue(RexNode node)

    • stringValue

      public static @Nullable String stringValue(RexNode node)

    • isNullLiteral

      public static boolean isNullLiteral(RexNode node)

    • accept

      public <R> R accept(RexVisitor<R> visitor)
      Description copied from class: RexNode
      Accepts a visitor, dispatching to the right overloaded visitXxx method.

      Also see RexUtil.apply(RexVisitor, java.util.List, RexNode), which applies a visitor to several expressions simultaneously.

      Specified by:
      accept in class RexNode

    • accept

      public <R, P> R accept(RexBiVisitor<R,P> visitor, P arg)
      Description copied from class: RexNode
      Accepts a visitor with a payload, dispatching to the right overloaded RexBiVisitor.visitInputRef(RexInputRef, Object) visitXxx} method.
      Specified by:
      accept in class RexNode