tribble.parse.sql
Class QueryExpr

java.lang.Object
  tribble.parse.sql.QueryExpr

All Implemented Interfaces:

java.lang.Cloneable

public class QueryExpr

extends java.lang.Object

implements java.lang.Cloneable

Query expression tree.

An object of this type is produced by a QueryParser object, which parses an SQL-like expression (i.e., an expression similar to an SQL 'SELECT WHERE' clause) and produces an expression tree in the form of a QueryExpr object.

Expression Trees

Some example query expressions and the expression trees resulting from parsing them:

Query	Expression Tree
exists	val "exists"
not directory	not val "directory"
not directory or writable	or not val "directory" val "writable"
name like "Sarah%Conner" and ( birth_date >= '1996-06-14' )	and like "name" "\"Sarah%Conner\"" ge "birth_date" "'1996-06-14'"
interest >= 5.000 and interest < 10.000	and ge "interest" "5.000" lt "interest" "10.000"
rec.id between 'A000' and 'B999'	between "rec.id" and "'A000'" "'B999'"
pay-type in ( 'WK' 'HR' 'YR' )	in "pay-type" list "'WK'" list "'HR'" list "'YR'"
addr is not null	not is "addr" "null"
rec.pay[mon]	subscr member "rec" "pay" "mon"

Since:

2001-03-24

Version:

$Revision: 1.10 $ $Date: 2007/08/01 03:14:02 $

Author:

David R. Tribble (david@tribble.com).

Copyright ©2001 by David R. Tribble, all rights reserved.
Permission is granted to any person or entity except those designated by by the United States Department of State as a terrorist, or terrorist government or agency, to use and distribute this source code provided that the original copyright notice remains present and unaltered.

See Also:

QueryParser

Field Summary

java.lang.Object	m_arg1 First (left) argument, typically either a QueryExpr or a String.
java.lang.Object	m_arg2 Second (right) argument, typically either a QueryExpr or a String.
java.lang.String	m_op Operator, one of the OP_XXX constants.
static java.lang.String	OP_ADD
static java.lang.String	OP_AND
static java.lang.String	OP_BETWEEN
static java.lang.String	OP_CONCAT
static java.lang.String	OP_CONTAINS
static java.lang.String	OP_DIV
static java.lang.String	OP_EQ
static java.lang.String	OP_EXPO
static java.lang.String	OP_GE
static java.lang.String	OP_GT
static java.lang.String	OP_IN
static java.lang.String	OP_IS
static java.lang.String	OP_LE
static java.lang.String	OP_LIKE
static java.lang.String	OP_LIKEFILE
static java.lang.String	OP_LIST
static java.lang.String	OP_LT
static java.lang.String	OP_MEMBER
static java.lang.String	OP_MOD
static java.lang.String	OP_MUL
static java.lang.String	OP_NE
static java.lang.String	OP_NEG
static java.lang.String	OP_NOP
static java.lang.String	OP_NOT
static java.lang.String	OP_NULL
static java.lang.String	OP_OR
static java.lang.String	OP_POS
static java.lang.String	OP_SUB
static java.lang.String	OP_SUBSCR
static java.lang.String	OP_VALUE
static int	SERIES

Constructor Summary

QueryExpr()
Default constructor.

Method Summary

protected static java.lang.String	asQuotedOperand(java.lang.String s) Add enclosing quotes to a string if necessary to make it a valid SQL token.
protected void	buildString(java.lang.Object arg, java.lang.StringBuffer text) Format an operand, appending it to a string buffer.
protected void	buildString(java.lang.StringBuffer text) Convert this expression subtree into a printable text string, appending it to a string buffer.
java.lang.Object	clone() Create a duplicate of this query expression tree.
void	dump(java.io.OutputStream out) Print the structure of this expression tree.
void	dump(java.io.Writer out) Print the structure of this expression tree.
protected void	dumpTree(java.io.PrintWriter out, java.lang.String indent) Print the structure of this expression tree.
static boolean	matchPattern(java.lang.String pat, java.lang.String s) Determine if a string matches a pattern string.
protected static int	matchSubpattern(java.lang.String pat, int patOff, java.lang.String str, int strOff) Determine if a substring matches a pattern substring.
void	simplify() Simplify this query expression tree.
java.lang.String	toString() Convert this expression tree into a printable text string.
protected void	writeAsXml(java.io.BufferedWriter out, java.lang.String indent) Print this query expression tree as XML.
void	writeAsXml(java.io.Writer out) Print this query expression tree as XML.
protected void	writeStringAsXml(java.io.BufferedWriter out, java.lang.String indent, java.lang.String arg) Print a query expression string argument tree as XML.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SERIES

public static final int SERIES

See Also:

Constant Field Values

OP_NOP

public static final java.lang.String OP_NOP

See Also:

Constant Field Values

OP_VALUE

public static final java.lang.String OP_VALUE

See Also:

Constant Field Values

OP_NOT

public static final java.lang.String OP_NOT

See Also:

Constant Field Values

OP_AND

public static final java.lang.String OP_AND

See Also:

Constant Field Values

OP_OR

public static final java.lang.String OP_OR

See Also:

Constant Field Values

OP_LIST

public static final java.lang.String OP_LIST

See Also:

Constant Field Values

OP_IS

public static final java.lang.String OP_IS

See Also:

Constant Field Values

OP_EQ

public static final java.lang.String OP_EQ

See Also:

Constant Field Values

OP_NE

public static final java.lang.String OP_NE

See Also:

Constant Field Values

OP_LT

public static final java.lang.String OP_LT

See Also:

Constant Field Values

OP_LE

public static final java.lang.String OP_LE

See Also:

Constant Field Values

OP_GT

public static final java.lang.String OP_GT

See Also:

Constant Field Values

OP_GE

public static final java.lang.String OP_GE

See Also:

Constant Field Values

OP_EXPO

public static final java.lang.String OP_EXPO

See Also:

Constant Field Values

OP_MUL

public static final java.lang.String OP_MUL

See Also:

Constant Field Values

OP_DIV

public static final java.lang.String OP_DIV

See Also:

Constant Field Values

OP_MOD

public static final java.lang.String OP_MOD

See Also:

Constant Field Values

OP_ADD

public static final java.lang.String OP_ADD

See Also:

Constant Field Values

OP_SUB

public static final java.lang.String OP_SUB

See Also:

Constant Field Values

OP_CONCAT

public static final java.lang.String OP_CONCAT

See Also:

Constant Field Values

OP_POS

public static final java.lang.String OP_POS

See Also:

Constant Field Values

OP_NEG

public static final java.lang.String OP_NEG

See Also:

Constant Field Values

OP_MEMBER

public static final java.lang.String OP_MEMBER

See Also:

Constant Field Values

OP_SUBSCR

public static final java.lang.String OP_SUBSCR

See Also:

Constant Field Values

OP_CONTAINS

public static final java.lang.String OP_CONTAINS

See Also:

Constant Field Values

OP_LIKE

public static final java.lang.String OP_LIKE

See Also:

Constant Field Values

OP_LIKEFILE

public static final java.lang.String OP_LIKEFILE

See Also:

Constant Field Values

OP_IN

public static final java.lang.String OP_IN

See Also:

Constant Field Values

OP_BETWEEN

public static final java.lang.String OP_BETWEEN

See Also:

Constant Field Values

OP_NULL

public static final java.lang.String OP_NULL

See Also:

Constant Field Values

m_op

public java.lang.String m_op

Operator, one of the OP_XXX constants.

m_arg1

public java.lang.Object m_arg1

First (left) argument, typically either a QueryExpr or a String.

m_arg2

public java.lang.Object m_arg2

Second (right) argument, typically either a QueryExpr or a String.

Constructor Detail

QueryExpr

public QueryExpr()

Default constructor.

Since:

1.1, 2001-03-13

Method Detail

matchPattern

public static boolean matchPattern(java.lang.String pat,
                                   java.lang.String s)

Determine if a string matches a pattern string.

Parameters:

pat - An SQL pattern string. A pattern is composed of regular characters and special pattern matching characters, which are:

_ (underscore) - Matches any single character.

% - Matches zero or more characters.

\ - Removes (escapes) the special meaning of the next character.

s - A string to compare against pattern pat.

Returns:

True if string s matches pattern pat, otherwise false.

Since:

1.2, 2001-03-28

matchSubpattern

protected static int matchSubpattern(java.lang.String pat,
                                     int patOff,
                                     java.lang.String str,
                                     int strOff)

Determine if a substring matches a pattern substring.

Parameters:

pat - A pattern string.

patOff - The index of the first (leftmost) character within pattern string pat to match.

str - A string to compare against pattern pat.

strOff - The index of the first (leftmost) character within string str to match.

Returns:

The index of one character past the last (rightmost) character within string str that matches pattern pat, or -1 if the substring does not match the pattern substring.

Since:

1.2, 2001-03-28

See Also:

matchPattern(java.lang.String, java.lang.String)

asQuotedOperand

protected static java.lang.String asQuotedOperand(java.lang.String s)

Add enclosing quotes to a string if necessary to make it a valid SQL token.

Parameters:

s - A string.

Returns:

The contents of string s, either unchanged or enclosed within quotes (").

Since:

1.9, 2001-04-16

toString

public java.lang.String toString()

Convert this expression tree into a printable text string.

Returns:

A text string representing this expression. (Note that the string is generated directly from the expression tree, and may not necessarily look the same as the original query expression that the tree was derived from.)

Since:

1.1, 2001-03-26

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Create a duplicate of this query expression tree.

Returns:

A deep-copy duplicate of this expression tree.

Throws:

java.lang.CloneNotSupportedException - Thrown if any of the node in this expression tree cannot be cloned.

Since:

1.5, 2001-04-01

writeAsXml

public void writeAsXml(java.io.Writer out)
                throws java.io.IOException

Print this query expression tree as XML.

For example, given the query expression:

    len > 80 and rec.type not = 'T' 

the following XML is generated for it:

    <query>
      <and>
        <gt>
          <arg>len</arg>
          <arg>80</arg>
        </gt>
        <not>
          <eq>
            <member>
              <arg>rec</arg>
              <arg>type</arg>
            </member>
            <arg>'T'</arg>
          </eq>
        </not>
      </and>
    </query> 

Parameters:

out - Output stream to write to.

Throws:

java.io.IOException - Thrown if an I/O (write) error occurs.

Since:

1.6, 2001-04-02

dump

public void dump(java.io.Writer out)

Print the structure of this expression tree.

Parameters:

out - An output stream to write to.

Since:

1.1, 2001-03-12

dump

public void dump(java.io.OutputStream out)

Print the structure of this expression tree.

Parameters:

out - An output stream to write to.

Since:

1.1, 2001-03-12

simplify

public void simplify()
              throws java.lang.Exception

Simplify this query expression tree.

Replaces the following query subexpressions with equivalent, but simpler, subexpressions:

    "X between A and B"   replaced with   "X >= A and X <= B"
    "X in ( A, B, C )"    replaced with   "X = A or X = B or X = C"
    "not X = A"           replaced with   "X <> A"
    "not not X = A"       replaced with   "X = A" 

In other words, the following subexpression trees are replaced with simpler equivalent subtrees:

Before	After
between "rec_id" and "'A000'" "'B999'"	and ge "rec_id" "'A000'" le "rec_id" "'B999'"
in "pay-type" list "'WK'" list "'HR'" list "'YR'"	or eq "pay-type" "'WK'" or eq "pay-type" "'HR'" eq "pay-type" "'YR'"
not gt "Amt" "25.00"	le "Amt" "25.00"
not not eq "Amt" "50.00"	eq "Amt" "50.00"

Throws:

java.lang.Exception - Thrown if this expression tree is malformed.

Since:

1.7, 2001-04-03

dumpTree

protected void dumpTree(java.io.PrintWriter out,
                        java.lang.String indent)

Print the structure of this expression tree.

This method is called by methods dump(Writer) and dump(OutputStream).

Example

Parsing the expression:

    name like "sarah%conner" and ( birth.date >= '1996-06-14' ) 

results in an expression tree that is printed like this:

    and
      like
        name
        "sarah%conner"
      ge
        birth.date
        '1996-06-14' 

Parameters:

out - An output stream to write to.

indent - Leading indentation.

Since:

1.1, 2001-03-12

See Also:

dump(Writer), dump(OutputStream)

buildString

protected void buildString(java.lang.StringBuffer text)

Convert this expression subtree into a printable text string, appending it to a string buffer.

This method is called by method toString().

Parameters:

text - A string buffer to append the text string representation of this subexpression to.

Since:

1.1, 2001-03-26

See Also:

toString()

buildString

protected void buildString(java.lang.Object arg,
                           java.lang.StringBuffer text)

Format an operand, appending it to a string buffer.

This method is called by method toString().

Parameters:

arg - An operand to append, which is either a String or an QueryExpr subtree. if it is a String, it will be delimited with quotes as necessary.

text - A string buffer to append the text string representation of this subexpression to.

Since:

1.3, 2001-03-30

See Also:

toString(), buildString(StringBuffer)

writeAsXml

protected void writeAsXml(java.io.BufferedWriter out,
                          java.lang.String indent)
                   throws java.io.IOException

Print this query expression tree as XML.

This method is called by method writeAsXml().

Parameters:

out - Output stream to write to.

indent - Indentation prefix for each line of XML text output.

Throws:

java.io.IOException - Thrown if an I/O (write) error occurs.

Since:

1.6, 2001-04-02

See Also:

writeAsXml

writeStringAsXml

protected void writeStringAsXml(java.io.BufferedWriter out,
                                java.lang.String indent,
                                java.lang.String arg)
                         throws java.io.IOException

Print a query expression string argument tree as XML.

This method is called by method writeAsXml().

Parameters:

out - Output stream to write to.

indent - Indentation prefix for each line of XML text output.

arg - An expression operand from a query expression tree.

Throws:

java.io.IOException - Thrown if an I/O (write) error occurs.

Since:

1.6, 2001-04-02

See Also:

writeAsXml