ADQLParser

java.lang.Object
- adql.parser.ADQLParser

All Implemented Interfaces:

ADQLParserConstants
```
public class ADQLParser
extends java.lang.Object
implements ADQLParserConstants
```
Parses an ADQL query thanks to the Query() function.
This parser is able, thanks to a QueryChecker object, to check each ADQLQuery just after its generation. It could be used to check the consistency between the ADQL query to parse and the "database" on which the query must be executed. By default, there is no QueryChecker. Thus you must extend QueryChecker to check semantically all generated ADQLQuery objects.

To create an object representation of the given ADQL query, this parser uses a ADQLQueryFactory object. So if you want customize some object (ie. CONTAINS) of this representation you just have to extend the corresponding default object (ie. ContainsFunction) and to extend the corresponding function of ADQLQueryFactory (ie. createContains(...)).

WARNING: To modify this class it's strongly encouraged to modify the .jj file in the section between PARSER_BEGIN and PARSER_END and to re-compile it with JavaCC.

Version:

1.4 (01/2018)

Author:

Grégory Mantelet (CDS;ARI) - gmantele@ari.uni-heidelberg.de

See Also:

QueryChecker, ADQLQueryFactory

Field Summary

Fields
Modifier and Type Field Description

Token jj_nt
Next token.

Token token
Current token.

ADQLParserTokenManager token_source
Generated Token Manager.
- Fields inherited from interface adql.parser.ADQLParserConstants
  ABS, ACOS, AND, AREA, AS, ASC, ASIN, ASTERISK, ATAN, ATAN2, AVG, BETWEEN, BOX, BY, CEILING, CENTROID, CIRCLE, COMMA, CONCAT, CONTAINS, COORD1, COORD2, COORDSYS, COS, COT, COUNT, DEFAULT, DEGREES, DELIMITED_IDENTIFIER, DESC, DIGIT, DISTANCE, DIVIDE, DOT, EOF, EOQ, EQUAL, EXISTS, EXP, FLOOR, FROM, FULL, GREATER_EQUAL_THAN, GREATER_THAN, GROUP, HAVING, IN, INNER, INTERSECTS, IS, JOIN, LEFT, LEFT_PAR, LESS_EQUAL_THAN, LESS_THAN, Letter, LIKE, LOG, LOG10, MAX, MIN, MINUS, MOD, NATURAL, NOT, NOT_EQUAL, NULL, ON, OR, ORDER, OUTER, PI, PLUS, POINT, POLYGON, POWER, QUANTIFIER, RADIANS, RAND, REGION, REGULAR_IDENTIFIER, RIGHT, RIGHT_PAR, ROUND, SCIENTIFIC_NUMBER, SELECT, SIN, SQL_RESERVED_WORD, SQRT, STRING_LITERAL, SUM, TAN, tokenImage, TOP, TRUNCATE, UNSIGNED_FLOAT, UNSIGNED_INTEGER, USING, WHERE, WithinDelimitedId, WithinString

Fields
Modifier and Type	Field	Description
`Token`	`jj_nt`	Next token.
`Token`	`token`	Current token.
`ADQLParserTokenManager`	`token_source`	Generated Token Manager.

Constructor Summary

Constructors
Constructor	Description
`ADQLParser()`	Builds an ADQL parser without a query to parse.
`ADQLParser(ADQLParserTokenManager tm)`	Constructor with generated Token Manager.
`ADQLParser(ADQLParserTokenManager tm, ADQLQueryFactory factory)`	Builds a parser with another token manager.
`ADQLParser(ADQLParserTokenManager tm, QueryChecker checker)`	Builds a parser with another token manager.
`ADQLParser(ADQLParserTokenManager tm, QueryChecker checker, ADQLQueryFactory factory)`	Builds a parser with another token manager.
`ADQLParser(ADQLQueryFactory factory)`	Builds an ADQL parser without a query to parse but with a `ADQLQueryFactory`.
`ADQLParser(QueryChecker checker)`	Builds an ADQL parser without a query to parse but with a `QueryChecker`.
`ADQLParser(QueryChecker checker, ADQLQueryFactory factory)`	Builds an ADQL parser without a query to parse but with a `QueryChecker` and a `ADQLQueryFactory`.
`ADQLParser(java.io.InputStream stream)`	Constructor with InputStream.
`ADQLParser(java.io.InputStream stream, ADQLQueryFactory factory)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.InputStream stream, QueryChecker checker)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.InputStream stream, QueryChecker checker, ADQLQueryFactory factory)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.InputStream stream, java.lang.String encoding)`	Constructor with InputStream and supplied encoding
`ADQLParser(java.io.InputStream stream, java.lang.String encoding, ADQLQueryFactory factory)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.InputStream stream, java.lang.String encoding, QueryChecker checker)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.InputStream stream, java.lang.String encoding, QueryChecker checker, ADQLQueryFactory factory)`	Builds a parser with a stream containing the query to parse.
`ADQLParser(java.io.Reader stream)`	Constructor.
`ADQLParser(java.io.Reader reader, ADQLQueryFactory factory)`	Builds a parser with a reader containing the query to parse.
`ADQLParser(java.io.Reader reader, QueryChecker checker)`	Builds a parser with a reader containing the query to parse.
`ADQLParser(java.io.Reader reader, QueryChecker checker, ADQLQueryFactory factory)`	Builds a parser with a reader containing the query to parse.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Between`	`BetweenEnd(ADQLOperand leftOp)`
`ADQLColumn`	`Column()`
`IdentifierItems`	`ColumnName()`	Extracts the name of a column with its possible catalog, schema and table prefixes.
`Comparison`	`ComparisonEnd(ADQLOperand leftOp)`
`ClauseConstraints`	`ConditionsList(ClauseConstraints clause)`
`ADQLConstraint`	`Constraint()`
`ADQLOperand[]`	`Coordinates()`
`ADQLOperand`	`CoordinateSystem()`
`void`	`disable_tracing()`	Disable tracing.
`void`	`enable_tracing()`	Enable tracing.
`GeometryFunction`	`ExtractCoordSys()`
`ADQLOperand`	`Factor()`
`void`	`From()`
`ParseException`	`generateParseException()`	Generate ParseException.
`GeometryFunction.GeometryValue<GeometryFunction>`	`GeometryExpression()`
`GeometryFunction`	`GeometryFunction()`
`GeometryFunction`	`GeometryValueFunction()`
`Token`	`getNextToken()`	Get the next Token.
`QueryChecker`	`getQueryChecker()`
`ADQLQueryFactory`	`getQueryFactory()`
`Token`	`getToken(int index)`	Get the specific Token.
`void`	`GroupBy()`
`void`	`Having()`
`IdentifierItems.IdentifierItem`	`Identifier()`
`In`	`InEnd(ADQLOperand leftOp)`
`FromContent`	`JoinedTable()`
`ADQLJoin`	`JoinSpecification(FromContent leftTable)`
`static void`	`main(java.lang.String[] args)`	Gets the specified ADQL query and parses the given ADQL query.
`MathFunction`	`MathFunction()`
`ADQLOperand`	`NumericExpression()`
`ADQLFunction`	`NumericFunction()`
`ADQLOperand`	`NumericTerm()`
`ADQLOperand`	`NumericValueExpressionPrimary()`
`void`	`OrderBy()`
`ADQLOrder`	`OrderItem()`
`ADQLQuery`	`parseQuery()`	Parses the query given at the creation of this parser or in the ReInit functions.
`ADQLQuery`	`parseQuery(java.io.InputStream stream)`	Parses the query contained in the stream given in parameter.
`ADQLQuery`	`parseQuery(java.lang.String q)`	Parses the query given in parameter.
`PointFunction`	`Point()`
`ADQLConstraint`	`Predicate()`
`ADQLQuery`	`Query()`	Parses the ADQL query given at the parser creation or in the `ReInit(java.io.InputStream)` or in the parseQuery functions.
`ADQLQuery`	`QueryExpression()`
`void`	`ReInit(ADQLParserTokenManager tm)`	Reinitialise.
`void`	`ReInit(java.io.InputStream stream)`	Reinitialise.
`void`	`ReInit(java.io.InputStream stream, java.lang.String encoding)`	Reinitialise.
`void`	`ReInit(java.io.Reader stream)`	Reinitialise.
`void`	`Select()`
`SelectItem`	`SelectItem()`
`void`	`setDebug(boolean debug)`
`void`	`setQueryChecker(QueryChecker checker)`
`void`	`setQueryFactory(ADQLQueryFactory factory)`
`NumericConstant`	`SignedInteger()`
`FromContent`	`SimpleTableRef()`
`SQLFunction`	`SqlFunction()`
`StringConstant`	`String()`
`ADQLOperand`	`StringExpression()`
`ADQLOperand`	`StringFactor()`
`ADQLOperand`	`StringValueExpressionPrimary()`
`ADQLQuery`	`SubQueryExpression()`
`IdentifierItems`	`TableName()`	Extracts the name of a table with its possible catalog and schema prefixes.
`FromContent`	`TableRef()`
`MathFunction`	`TrigFunction()`
`NumericConstant`	`UnsignedFloat()`
`NumericConstant`	`UnsignedNumeric()`
`UserDefinedFunction`	`UserDefinedFunction()`
`ADQLOperand`	`ValueExpression()`
`void`	`Where()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

token_source

public ADQLParserTokenManager token_source

Generated Token Manager.

token
```
public Token token
```
Current token.

jj_nt
```
public Token jj_nt
```
Next token.

Constructor Detail
- ADQLParser
```
public ADQLParser()
```
  Builds an ADQL parser without a query to parse.
- ADQLParser
```
public ADQLParser(QueryChecker checker,
                  ADQLQueryFactory factory)
```
  Builds an ADQL parser without a query to parse but with a QueryChecker and a ADQLQueryFactory.
  
  Parameters:
  
  checker - The object to use to check each ADQLQuery.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(QueryChecker checker)
```
  Builds an ADQL parser without a query to parse but with a QueryChecker.
  
  Parameters:
  
  checker - The object to use to check each ADQLQuery.
- ADQLParser
```
public ADQLParser(ADQLQueryFactory factory)
```
  Builds an ADQL parser without a query to parse but with a ADQLQueryFactory.
  
  Parameters:
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  QueryChecker checker,
                  ADQLQueryFactory factory)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  checker - The object to use to check each ADQLQuery.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  QueryChecker checker)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  checker - The object to use to check each ADQLQuery.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  ADQLQueryFactory factory)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  java.lang.String encoding,
                  QueryChecker checker,
                  ADQLQueryFactory factory)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  encoding - The supplied encoding.
  
  checker - The object to use to check each ADQLQuery.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  java.lang.String encoding,
                  QueryChecker checker)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  encoding - The supplied encoding.
  
  checker - The object to use to check each ADQLQuery.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  java.lang.String encoding,
                  ADQLQueryFactory factory)
```
  Builds a parser with a stream containing the query to parse.
  
  Parameters:
  
  stream - The stream in which the ADQL query to parse is given.
  
  encoding - The supplied encoding.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.Reader reader,
                  QueryChecker checker,
                  ADQLQueryFactory factory)
```
  Builds a parser with a reader containing the query to parse.
  
  Parameters:
  
  reader - The reader in which the ADQL query to parse is given.
  
  checker - The object to use to check each ADQLQuery.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.Reader reader,
                  QueryChecker checker)
```
  Builds a parser with a reader containing the query to parse.
  
  Parameters:
  
  reader - The reader in which the ADQL query to parse is given.
  
  checker - The object to use to check each ADQLQuery.
- ADQLParser
```
public ADQLParser(java.io.Reader reader,
                  ADQLQueryFactory factory)
```
  Builds a parser with a reader containing the query to parse.
  
  Parameters:
  
  reader - The reader in which the ADQL query to parse is given.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(ADQLParserTokenManager tm,
                  QueryChecker checker,
                  ADQLQueryFactory factory)
```
  Builds a parser with another token manager.
  
  Parameters:
  
  tm - The manager which associates a token to a numeric code.
  
  checker - The object to use to check each ADQLQuery.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(ADQLParserTokenManager tm,
                  QueryChecker checker)
```
  Builds a parser with another token manager.
  
  Parameters:
  
  tm - The manager which associates a token to a numeric code.
  
  checker - The object to use to check each ADQLQuery.
- ADQLParser
```
public ADQLParser(ADQLParserTokenManager tm,
                  ADQLQueryFactory factory)
```
  Builds a parser with another token manager.
  
  Parameters:
  
  tm - The manager which associates a token to a numeric code.
  
  factory - The object to use to build an object representation of the given ADQL query.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream)
```
  Constructor with InputStream.
- ADQLParser
```
public ADQLParser(java.io.InputStream stream,
                  java.lang.String encoding)
```
  Constructor with InputStream and supplied encoding
- ADQLParser
```
public ADQLParser(java.io.Reader stream)
```
  Constructor.
- ADQLParser
```
public ADQLParser(ADQLParserTokenManager tm)
```
  Constructor with generated Token Manager.

Method Detail

parseQuery
```
public final ADQLQuery parseQuery()
                           throws ParseException
```
Parses the query given at the creation of this parser or in the ReInit functions.

Returns:

The object representation of the given ADQL query.

Throws:

ParseException - If there is at least one syntactic error.

See Also:

Query()

parseQuery
```
public final ADQLQuery parseQuery(java.lang.String q)
                           throws ParseException
```
Parses the query given in parameter.

Parameters:

q - The ADQL query to parse.

Returns:

The object representation of the given ADQL query.

Throws:

ParseException - If there is at least one syntactic error.

See Also:

ReInit(java.io.InputStream), setDebug(boolean), Query()

parseQuery
```
public final ADQLQuery parseQuery(java.io.InputStream stream)
                           throws ParseException
```
Parses the query contained in the stream given in parameter.

Parameters:

stream - The stream which contains the ADQL query to parse.

Returns:

The object representation of the given ADQL query.

Throws:

ParseException - If there is at least one syntactic error.

See Also:

ReInit(java.io.InputStream), setDebug(boolean), Query()

setDebug

public final void setDebug(boolean debug)

getQueryChecker

public final QueryChecker getQueryChecker()

setQueryChecker

public final void setQueryChecker(QueryChecker checker)

getQueryFactory

public final ADQLQueryFactory getQueryFactory()

setQueryFactory

public final void setQueryFactory(ADQLQueryFactory factory)

main
```
public static final void main(java.lang.String[] args)
                       throws java.lang.Exception
```
Gets the specified ADQL query and parses the given ADQL query. The SQL translation is then printed if the syntax is correct.
ONLY the syntax is checked: the query is NOT EXECUTED !

Supplied parameters are:
- [-debug] -url http://...
- [-debug] -file ...
- [-debug] -query SELECT...
Parameters:

args -

Throws:

java.lang.Exception

Query
```
public final ADQLQuery Query()
                      throws ParseException
```
Parses the ADQL query given at the parser creation or in the ReInit(java.io.InputStream) or in the parseQuery functions.

Returns:

The object representation of the query.

Throws:

ParseException - If the query syntax is incorrect.

QueryExpression

public final ADQLQuery QueryExpression()
                                throws ParseException

Throws:: ParseException

SubQueryExpression

public final ADQLQuery SubQueryExpression()
                                   throws ParseException

Throws:: ParseException

Select

public final void Select()
                  throws ParseException

Throws:: ParseException

SelectItem

public final SelectItem SelectItem()
                            throws ParseException

Throws:: ParseException

From

public final void From()
                throws ParseException

Throws:: ParseException

Where

public final void Where()
                 throws ParseException

Throws:: ParseException

GroupBy

public final void GroupBy()
                   throws ParseException

Throws:: ParseException

Having

public final void Having()
                  throws ParseException

Throws:: ParseException

OrderBy

public final void OrderBy()
                   throws ParseException

Throws:: ParseException

Identifier

public final IdentifierItems.IdentifierItem Identifier()
                                                throws ParseException

Throws:: ParseException

TableName
```
public final IdentifierItems TableName()
                                throws ParseException
```
Extracts the name of a table with its possible catalog and schema prefixes.

Returns:

A IdentifierItems which contains at most three items: catalogName, schemaName and tableName.

Throws:

ParseException

ColumnName
```
public final IdentifierItems ColumnName()
                                 throws ParseException
```
Extracts the name of a column with its possible catalog, schema and table prefixes.

Returns:

A IdentifierItems which contains at most four items: catalogName, schemaName, tableName and columnName.

Throws:

ParseException

Column

public final ADQLColumn Column()
                        throws ParseException

Throws:: ParseException

OrderItem

public final ADQLOrder OrderItem()
                          throws ParseException

Throws:: ParseException

SimpleTableRef

public final FromContent SimpleTableRef()
                                 throws ParseException

Throws:: ParseException

TableRef

public final FromContent TableRef()
                           throws ParseException

Throws:: ParseException

JoinedTable

public final FromContent JoinedTable()
                              throws ParseException

Throws:: ParseException

JoinSpecification

public final ADQLJoin JoinSpecification(FromContent leftTable)
                                 throws ParseException

Throws:: ParseException

String

public final StringConstant String()
                            throws ParseException

Throws:: ParseException

UnsignedNumeric

public final NumericConstant UnsignedNumeric()
                                      throws ParseException

Throws:: ParseException

UnsignedFloat

public final NumericConstant UnsignedFloat()
                                    throws ParseException

Throws:: ParseException

SignedInteger

public final NumericConstant SignedInteger()
                                    throws ParseException

Throws:: ParseException

NumericValueExpressionPrimary

public final ADQLOperand NumericValueExpressionPrimary()
                                                throws ParseException

Throws:: ParseException

StringValueExpressionPrimary

public final ADQLOperand StringValueExpressionPrimary()
                                               throws ParseException

Throws:: ParseException

ValueExpression

public final ADQLOperand ValueExpression()
                                  throws ParseException

Throws:: ParseException

NumericExpression

public final ADQLOperand NumericExpression()
                                    throws ParseException

Throws:: ParseException

NumericTerm

public final ADQLOperand NumericTerm()
                              throws ParseException

Throws:: ParseException

Factor

public final ADQLOperand Factor()
                         throws ParseException

Throws:: ParseException

StringExpression

public final ADQLOperand StringExpression()
                                   throws ParseException

Throws:: ParseException

StringFactor

public final ADQLOperand StringFactor()
                               throws ParseException

Throws:: ParseException

GeometryExpression

public final GeometryFunction.GeometryValue<GeometryFunction> GeometryExpression()
                                                                          throws ParseException

Throws:: ParseException

ConditionsList

public final ClauseConstraints ConditionsList(ClauseConstraints clause)
                                       throws ParseException

Throws:: ParseException

Constraint

public final ADQLConstraint Constraint()
                                throws ParseException

Throws:: ParseException

Predicate

public final ADQLConstraint Predicate()
                               throws ParseException

Throws:: ParseException

ComparisonEnd

public final Comparison ComparisonEnd(ADQLOperand leftOp)
                               throws ParseException

Throws:: ParseException

BetweenEnd

public final Between BetweenEnd(ADQLOperand leftOp)
                         throws ParseException

Throws:: ParseException

InEnd

public final In InEnd(ADQLOperand leftOp)
               throws ParseException

Throws:: ParseException

SqlFunction

public final SQLFunction SqlFunction()
                              throws ParseException

Throws:: ParseException

Coordinates

public final ADQLOperand[] Coordinates()
                                throws ParseException

Throws:: ParseException

GeometryFunction

public final GeometryFunction GeometryFunction()
                                        throws ParseException

Throws:: ParseException

CoordinateSystem

public final ADQLOperand CoordinateSystem()
                                   throws ParseException

Throws:: ParseException

GeometryValueFunction

public final GeometryFunction GeometryValueFunction()
                                             throws ParseException

Throws:: ParseException

Point

public final PointFunction Point()
                          throws ParseException

Throws:: ParseException

ExtractCoordSys

public final GeometryFunction ExtractCoordSys()
                                       throws ParseException

Throws:: ParseException

NumericFunction

public final ADQLFunction NumericFunction()
                                   throws ParseException

Throws:: ParseException

MathFunction

public final MathFunction MathFunction()
                                throws ParseException

Throws:: ParseException

TrigFunction

public final MathFunction TrigFunction()
                                throws ParseException

Throws:: ParseException

UserDefinedFunction

public final UserDefinedFunction UserDefinedFunction()
                                              throws ParseException

Throws:: ParseException

ReInit

public void ReInit(java.io.InputStream stream)

Reinitialise.

ReInit

public void ReInit(java.io.InputStream stream,
                   java.lang.String encoding)

Reinitialise.

ReInit

public void ReInit(java.io.Reader stream)

Reinitialise.

ReInit

public void ReInit(ADQLParserTokenManager tm)

Reinitialise.

getNextToken
```
public final Token getNextToken()
```
Get the next Token.

getToken

public final Token getToken(int index)

Get the specific Token.

generateParseException

public ParseException generateParseException()

Generate ParseException.

enable_tracing
```
public final void enable_tracing()
```
Enable tracing.

disable_tracing

public final void disable_tracing()

Disable tracing.

Class ADQLParser

Field Summary

Fields inherited from interface adql.parser.ADQLParserConstants

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

token_source

token

jj_nt

Constructor Detail

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

ADQLParser

Method Detail

parseQuery

parseQuery

parseQuery

setDebug

getQueryChecker

setQueryChecker

getQueryFactory

setQueryFactory

main

Query

QueryExpression

SubQueryExpression

Select

SelectItem

From

Where

GroupBy

Having

OrderBy

Identifier

TableName

ColumnName

Column

OrderItem

SimpleTableRef

TableRef

JoinedTable

JoinSpecification

String

UnsignedNumeric

UnsignedFloat

SignedInteger

NumericValueExpressionPrimary

StringValueExpressionPrimary

ValueExpression

NumericExpression

NumericTerm

Factor

StringExpression

StringFactor

GeometryExpression

ConditionsList

Constraint

Predicate

ComparisonEnd

BetweenEnd

InEnd

SqlFunction