PhysType (Calcite Core 1.2.0-incubating API)

All Known Implementing Classes:

PhysTypeImpl
```
public interface PhysType
```
Physical type of a row.
Consists of the SQL row type (returned by getRowType()), the Java type of the row (returned by getJavaRowType()), and methods to generate expressions to access fields, generate records, and so forth. Together, the records encapsulate how the logical type maps onto the physical type.

Method Summary

Methods
Modifier and Type	Method and Description
`List<Expression>`	`accessors(Expression parameter, List<Integer> argList)`
`Expression`	`comparer()` Returns a expression that yields a comparer, or null if this type is comparable.
`Expression`	`convertTo(Expression expression, PhysType targetPhysType)` Converts an enumerable of this physical type to an enumerable that uses a given physical type for its rows.
`Class`	`fieldClass(int field)` Returns the Java class of the field with the given ordinal.
`boolean`	`fieldNullable(int index)` Returns whether a given field allows null values.
`Expression`	`fieldReference(Expression expression, int field)` Generates a reference to a given field in an expression.
`Expression`	`fieldReference(Expression expression, int field, Type storageType)` Generates a reference to a given field in an expression.
`Expression`	`generateAccessor(List<Integer> fields)` Generates an accessor function for a given list of fields.
`Pair<Expression,Expression>`	`generateCollationKey(List<RelFieldCollation> collations)` Returns a lambda to create a collation key and a comparator.
`Expression`	`generateComparator(RelCollation collation)` Returns a comparator.
`Expression`	`generateSelector(ParameterExpression parameter, List<Integer> fields)` Generates a selector for the given fields from an expression, with the default row format.
`Expression`	`generateSelector(ParameterExpression parameter, List<Integer> fields, JavaRowFormat targetFormat)` Generates a lambda expression that is a selector for the given fields from an expression.
`Expression`	`generateSelector(ParameterExpression parameter, List<Integer> fields, List<Integer> usedFields, JavaRowFormat targetFormat)` Generates a lambda expression that is a selector for the given fields from an expression.
`JavaRowFormat`	`getFormat()` Returns the format.
`Type`	`getJavaFieldType(int field)` Returns the Java class that is used to store the field with the given ordinal.
`Type`	`getJavaRowType()` Returns the Java type (often a Class) that represents a row.
`RelDataType`	`getRowType()` Returns the SQL row type.
`PhysType`	`makeNullable(boolean nullable)` Returns a copy of this type that allows nulls if `nullable` is true.
`PhysType`	`project(List<Integer> integers, boolean indicator, JavaRowFormat format)` Projects a given collection of fields from this input record, optionally with indicator fields, into a particular preferred output format.
`PhysType`	`project(List<Integer> integers, JavaRowFormat format)` Projects a given collection of fields from this input record, into a particular preferred output format.
`Expression`	`record(List<Expression> expressions)` Generates an expression that creates a record for a row, initializing its fields with the given expressions.
`Expression`	`selector(ParameterExpression parameter, List<Integer> fields, JavaRowFormat targetFormat)` Generates a selector for the given fields from an expression.

- Method Detail
  - getJavaRowType
```
Type getJavaRowType()
```
    Returns the Java type (often a Class) that represents a row. For example, in one row format, always returns Object[].class.
  - getJavaFieldType
```
Type getJavaFieldType(int field)
```
    Returns the Java class that is used to store the field with the given ordinal.
    For instance, when the java row type is Object[], the java field type is Object even if the field is not nullable.
  - getRowType
```
RelDataType getRowType()
```
    Returns the SQL row type.
  - fieldClass
```
Class fieldClass(int field)
```
    Returns the Java class of the field with the given ordinal.
  - fieldNullable
```
boolean fieldNullable(int index)
```
    Returns whether a given field allows null values.
  - fieldReference
```
Expression fieldReference(Expression expression,
                        int field)
```
    Generates a reference to a given field in an expression.
    For example given expression=employee and field=2, generates
```
employee.deptno
```
    Parameters:
    expression - Expression
    field - Ordinal of field
    
    Returns:
    Expression to access the field of the expression
  - fieldReference
```
Expression fieldReference(Expression expression,
                        int field,
                        Type storageType)
```
    Generates a reference to a given field in an expression.
    This method optimizes for the target storage type (i.e. avoids casts).
    
    For example given expression=employee and field=2, generates
```
employee.deptno
```
    Parameters:
    expression - Expression
    field - Ordinal of field
    storageType - optional hint for storage class
    
    Returns:
    Expression to access the field of the expression
  - generateAccessor
```
Expression generateAccessor(List<Integer> fields)
```
    Generates an accessor function for a given list of fields. The resulting object is a List (implementing Object.hashCode() and Object.equals(Object) per that interface) and also implements Comparable.
    For example:
```
new Function1<Employee, Object[]> {
    public Object[] apply(Employee v1) {
        return FlatLists.of(v1.<fieldN>, v1.<fieldM>);
    }
 }
 
```
  - generateSelector
```
Expression generateSelector(ParameterExpression parameter,
                          List<Integer> fields)
```
    Generates a selector for the given fields from an expression, with the default row format.
  - generateSelector
```
Expression generateSelector(ParameterExpression parameter,
                          List<Integer> fields,
                          JavaRowFormat targetFormat)
```
    Generates a lambda expression that is a selector for the given fields from an expression.
  - generateSelector
```
Expression generateSelector(ParameterExpression parameter,
                          List<Integer> fields,
                          List<Integer> usedFields,
                          JavaRowFormat targetFormat)
```
    Generates a lambda expression that is a selector for the given fields from an expression.
    usedFields must be a subset of fields. For each field, there is a corresponding indicator field. If a field is used, its value is assigned and its indicator is left false. If a field is not used, its value is not assigned and its indicator is set to true; This will become a value of 1 when GROUPING(field) is called.
  - selector
```
Expression selector(ParameterExpression parameter,
                  List<Integer> fields,
                  JavaRowFormat targetFormat)
```
    Generates a selector for the given fields from an expression.
  - project
```
PhysType project(List<Integer> integers,
               JavaRowFormat format)
```
    Projects a given collection of fields from this input record, into a particular preferred output format. The output format is optimized if there are 0 or 1 fields.
  - project
```
PhysType project(List<Integer> integers,
               boolean indicator,
               JavaRowFormat format)
```
    Projects a given collection of fields from this input record, optionally with indicator fields, into a particular preferred output format.
    The output format is optimized if there are 0 or 1 fields and indicators are disabled.
  - generateCollationKey
```
Pair<Expression,Expression> generateCollationKey(List<RelFieldCollation> collations)
```
    Returns a lambda to create a collation key and a comparator. The comparator is sometimes null.
  - generateComparator
```
Expression generateComparator(RelCollation collation)
```
    Returns a comparator. Unlike the comparator returned by generateCollationKey(java.util.List), this comparator acts on the whole element.
  - comparer
```
Expression comparer()
```
    Returns a expression that yields a comparer, or null if this type is comparable.
  - record
```
Expression record(List<Expression> expressions)
```
    Generates an expression that creates a record for a row, initializing its fields with the given expressions. There must be one expression per field.
    
    Parameters:
    expressions - Expression to initialize each field
    
    Returns:
    Expression to create a row
  - getFormat
```
JavaRowFormat getFormat()
```
    Returns the format.
  - accessors
```
List<Expression> accessors(Expression parameter,
                         List<Integer> argList)
```
  - makeNullable
```
PhysType makeNullable(boolean nullable)
```
    Returns a copy of this type that allows nulls if nullable is true.
  - convertTo
```
Expression convertTo(Expression expression,
                   PhysType targetPhysType)
```
    Converts an enumerable of this physical type to an enumerable that uses a given physical type for its rows.

Interface PhysType

Method Summary

Method Detail

getJavaRowType

getJavaFieldType

getRowType

fieldClass

fieldNullable

fieldReference

fieldReference

generateAccessor

generateSelector

generateSelector

generateSelector

selector

project

project

generateCollationKey

generateComparator

comparer

record

getFormat

accessors

makeNullable

convertTo