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jackcess/src/main/java/com/healthmarketscience/jackcess/expr/package-info.java

package-info.java 12KB
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  1. /*

  2. Copyright (c) 2018 James Ahlborn

  3. 

  4. Licensed under the Apache License, Version 2.0 (the "License");

  5. you may not use this file except in compliance with the License.

  6. You may obtain a copy of the License at

  7. 

  8.     http://www.apache.org/licenses/LICENSE-2.0

  9. 

  10. Unless required by applicable law or agreed to in writing, software

  11. distributed under the License is distributed on an "AS IS" BASIS,

  12. WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  13. See the License for the specific language governing permissions and

  14. limitations under the License.

  15. */

  16. 

  17. /**

  18.  * Jackcess has support for evaluating Access expressions (beta support as of

  19.  * the 2.2.0 release).  This functionality is currently disabled by default

  20.  * but can be globally enabled via the system property

  21.  * "com.healthmarketscience.jackcess.enableExpressionEvaluation" or

  22.  * selectively enabled on a per database basis using {@link com.healthmarketscience.jackcess.Database#setEvaluateExpressions(Boolean)}.

  23.  * <p/>

  24.  * The expression evaluation engine implementation does its best to follow all

  25.  * the warts and idiosyncracies of Access expression evaluation (both those

  26.  * that are documented as well as those discovered through experimentation).

  27.  * These include such things as value conversions, "Null" handling, rounding

  28.  * rules, and implicit interpretations of expression in certain contexts.

  29.  * <p/>

  30.  * Expressions can be used in a number of different places within an Access

  31.  * database.  When enabled, Jackcess supports the following usage:

  32.  * <ul>

  33.  *   <li><b>Default Values:</b> When a row is added which has a

  34.  *       {@code null} value for a field which has a default value

  35.  *       expression defined, that expression will be evaluated and the

  36.  *       result will be inserted for that field.  Like an auto-generated

  37.  *       id, the generated default value will be returned in the input

  38.  *       row array.</li>

  39.  *   <li><b>Calculated Fields:</b> In databases which support calculated

  40.  *       fields, any input value for a calculated field will be ignored.

  41.  *       Instead, the result of evaluating the calculated field

  42.  *       expression will be inserted.  Like an auto-generated id, the

  43.  *       calculated value will be returned in the input row array.</li>

  44.  *   <li><b>Field Validation:</b> Field validation rules will be

  45.  *       evaluated whenever a field value is updated.  If the rule fails,

  46.  *       the update operation will fail.  The failure message will

  47.  *       specify which field's validation rule failed and include the

  48.  *       custom validation rule message if defined.</li>

  49.  *   <li><b>Record Validation:</b> Similar to field validation rules,

  50.  *       record validation rules will be run for the entire record before

  51.  *       update.  Failures are handled in a similar manner.</li>

  52.  * </ul>

  53.  * <p/>

  54.  * <h2>Supporting Classes</h2>

  55.  * <p/>

  56.  * The classes in this package make up the public api for expression handling

  57.  * in Jackcess.  They generally fall into two categories:

  58.  * <p/>

  59.  * <h3>General Use Classes</h3>

  60.  * <p/>

  61.  * <ul>

  62.  * <li>{@link com.healthmarketscience.jackcess.expr.EvalConfig} allows for customization of the expression

  63.  *     evaluation context for a given {@link com.healthmarketscience.jackcess.Database} instance.</li>

  64.  * <li>{@link com.healthmarketscience.jackcess.expr.TemporalConfig} encapsulates date/time formatting options for

  65.  *     expression evaluation.</li>

  66.  * <li>{@link com.healthmarketscience.jackcess.expr.NumericConfig} encapsulates number formatting options for

  67.  *     expression evaluation.</li>

  68.  * <li>{@link com.healthmarketscience.jackcess.expr.FunctionLookup} provides a source for {@link com.healthmarketscience.jackcess.expr.Function} instances

  69.  *     used during expression evaluation.</li>

  70.  * <li>{@link com.healthmarketscience.jackcess.expr.EvalException} wrapper exception thrown for failures which occur

  71.  *     during expression evaluation.</li>

  72.  * <li>{@link com.healthmarketscience.jackcess.expr.ParseException} wrapper exception thrown for failures which

  73.  *     occur during expression parsing.</li>

  74.  * </ul>

  75.  * <p/>

  76.  * <h3>Advanced Use Classes</h3>

  77.  * <p/>

  78.  * <ul>

  79.  * <li>{@link com.healthmarketscience.jackcess.expr.EvalContext} encapsulates all shared state for expression

  80.  *     parsing and evaluation.</li>

  81.  * <li>{@link com.healthmarketscience.jackcess.expr.Expression} provides an executable handle to an actual

  82.  *     Access expression.</li>

  83.  * <li>{@link com.healthmarketscience.jackcess.expr.Function} provides an invokable handle to external functionality

  84.  *     to an expression.</li>

  85.  * <li>{@link com.healthmarketscience.jackcess.expr.Identifier} identifies a database entity (e.g. the name of a

  86.  *     database field).</li>

  87.  * <li>{@link com.healthmarketscience.jackcess.expr.Value} represents a typed primitive value.</li>

  88.  * </ul>

  89.  * <p/>

  90.  * <h2>Function Support</h2>

  91.  * <p/>

  92.  * Jackcess supports many of the standard Access functions.  The following

  93.  * tables list the (hopefully) current status of support built into Jackcess.

  94.  *

  95.  * <h3>Conversion</h3>

  96.  *

  97.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  98.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  99.  * <tr class="TableRowColor"><td>Asc</td><td>Y</td></tr>

  100.  * <tr class="TableRowColor"><td>AscW</td><td>Y</td></tr>

  101.  * <tr class="TableRowColor"><td>Chr</td><td>Y</td></tr>

  102.  * <tr class="TableRowColor"><td>ChrW</td><td>Y</td></tr>

  103.  * <tr class="TableRowColor"><td>EuroConvert</td><td></td></tr>

  104.  * <tr class="TableRowColor"><td>FormatCurrency</td><td></td></tr>

  105.  * <tr class="TableRowColor"><td>FormatDateTime</td><td></td></tr>

  106.  * <tr class="TableRowColor"><td>FormatNumber</td><td></td></tr>

  107.  * <tr class="TableRowColor"><td>FormatPercent</td><td></td></tr>

  108.  * <tr class="TableRowColor"><td>GUIDFromString</td><td></td></tr>

  109.  * <tr class="TableRowColor"><td>Hex[$]</td><td>Y</td></tr>

  110.  * <tr class="TableRowColor"><td>Nz</td><td>Y</td></tr>

  111.  * <tr class="TableRowColor"><td>Oct[$]</td><td>Y</td></tr>

  112.  * <tr class="TableRowColor"><td>Str[$]</td><td>Y</td></tr>

  113.  * <tr class="TableRowColor"><td>StringFromGUID</td><td></td></tr>

  114.  * <tr class="TableRowColor"><td>Val</td><td>Y</td></tr>

  115.  * <tr class="TableRowColor"><td>CBool</td><td>Y</td></tr>

  116.  * <tr class="TableRowColor"><td>CByte</td><td>Y</td></tr>

  117.  * <tr class="TableRowColor"><td>CCur</td><td>Y</td></tr>

  118.  * <tr class="TableRowColor"><td>CDate</td><td>Y</td></tr>

  119.  * <tr class="TableRowColor"><td>CVDate</td><td>Y</td></tr>

  120.  * <tr class="TableRowColor"><td>CDbl</td><td>Y</td></tr>

  121.  * <tr class="TableRowColor"><td>CDec</td><td>Y</td></tr>

  122.  * <tr class="TableRowColor"><td>CInt</td><td>Y</td></tr>

  123.  * <tr class="TableRowColor"><td>CLng</td><td>Y</td></tr>

  124.  * <tr class="TableRowColor"><td>CSng</td><td>Y</td></tr>

  125.  * <tr class="TableRowColor"><td>CStr</td><td>Y</td></tr>

  126.  * <tr class="TableRowColor"><td>CVar</td><td>Y</td></tr>

  127.  * </table>

  128.  *

  129.  * <h3>Date/Time</h3>

  130.  *

  131.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  132.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  133.  * <tr class="TableRowColor"><td>Day</td><td>Y</td></tr>

  134.  * <tr class="TableRowColor"><td>Date </td><td>Y</td></tr>

  135.  * <tr class="TableRowColor"><td>DateAdd</td><td>Y</td></tr>

  136.  * <tr class="TableRowColor"><td>DateDiff</td><td></td></tr>

  137.  * <tr class="TableRowColor"><td>DatePart</td><td>Y</td></tr>

  138.  * <tr class="TableRowColor"><td>DateSerial</td><td>Y</td></tr>

  139.  * <tr class="TableRowColor"><td>DateValue</td><td>Y</td></tr>

  140.  * <tr class="TableRowColor"><td>Hour</td><td>Y</td></tr>

  141.  * <tr class="TableRowColor"><td>Minute</td><td>Y</td></tr>

  142.  * <tr class="TableRowColor"><td>Month</td><td>Y</td></tr>

  143.  * <tr class="TableRowColor"><td>MonthName</td><td>Y</td></tr>

  144.  * <tr class="TableRowColor"><td>Now</td><td>Y</td></tr>

  145.  * <tr class="TableRowColor"><td>Second</td><td>Y</td></tr>

  146.  * <tr class="TableRowColor"><td>Time</td><td>Y</td></tr>

  147.  * <tr class="TableRowColor"><td>Timer</td><td>Y</td></tr>

  148.  * <tr class="TableRowColor"><td>TimeSerial</td><td>Y</td></tr>

  149.  * <tr class="TableRowColor"><td>TimeValue</td><td>Y</td></tr>

  150.  * <tr class="TableRowColor"><td>Weekday</td><td>Y</td></tr>

  151.  * <tr class="TableRowColor"><td>WeekdayName</td><td>Y</td></tr>

  152.  * <tr class="TableRowColor"><td>Year</td><td>Y</td></tr>

  153.  * </table>

  154.  *

  155.  * <h3>Financial</h3>

  156.  *

  157.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  158.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  159.  * <tr class="TableRowColor"><td>DDB</td><td>Y</td></tr>

  160.  * <tr class="TableRowColor"><td>FV</td><td>Y</td></tr>

  161.  * <tr class="TableRowColor"><td>IPmt</td><td>Y</td></tr>

  162.  * <tr class="TableRowColor"><td>NPer</td><td>Y</td></tr>

  163.  * <tr class="TableRowColor"><td>Pmt</td><td>Y</td></tr>

  164.  * <tr class="TableRowColor"><td>PPmt</td><td>Y</td></tr>

  165.  * <tr class="TableRowColor"><td>PV</td><td>Y</td></tr>

  166.  * <tr class="TableRowColor"><td>Rate</td><td>Y</td></tr>

  167.  * <tr class="TableRowColor"><td>SLN</td><td>Y</td></tr>

  168.  * <tr class="TableRowColor"><td>SYD</td><td>Y</td></tr>

  169.  * </table>

  170.  *

  171.  * <h3>Inspection</h3>

  172.  *

  173.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  174.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  175.  * <tr class="TableRowColor"><td>IsDate</td><td>Partial</td></tr>

  176.  * <tr class="TableRowColor"><td>IsEmpty</td><td></td></tr>

  177.  * <tr class="TableRowColor"><td>IsError</td><td></td></tr>

  178.  * <tr class="TableRowColor"><td>IsMissing</td><td></td></tr>

  179.  * <tr class="TableRowColor"><td>IsNull</td><td>Y</td></tr>

  180.  * <tr class="TableRowColor"><td>IsNumeric</td><td>Y</td></tr>

  181.  * <tr class="TableRowColor"><td>IsObject</td><td></td></tr>

  182.  * <tr class="TableRowColor"><td>TypeName</td><td>Y</td></tr>

  183.  * <tr class="TableRowColor"><td>VarType</td><td>Y</td></tr>

  184.  * </table>

  185.  *

  186.  * <h3>Math</h3>

  187.  *

  188.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  189.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  190.  * <tr class="TableRowColor"><td>Abs</td><td>Y</td></tr>

  191.  * <tr class="TableRowColor"><td>Atn</td><td>Y</td></tr>

  192.  * <tr class="TableRowColor"><td>Cos</td><td>Y</td></tr>

  193.  * <tr class="TableRowColor"><td>Exp</td><td>Y</td></tr>

  194.  * <tr class="TableRowColor"><td>Int</td><td>Y</td></tr>

  195.  * <tr class="TableRowColor"><td>Fix</td><td>Y</td></tr>

  196.  * <tr class="TableRowColor"><td>Log</td><td>Y</td></tr>

  197.  * <tr class="TableRowColor"><td>Rnd</td><td>Y</td></tr>

  198.  * <tr class="TableRowColor"><td>Round</td><td>Y</td></tr>

  199.  * <tr class="TableRowColor"><td>Sgn</td><td>Y</td></tr>

  200.  * <tr class="TableRowColor"><td>Sin</td><td>Y</td></tr>

  201.  * <tr class="TableRowColor"><td>Sqr</td><td>Y</td></tr>

  202.  * <tr class="TableRowColor"><td>Tan</td><td>Y</td></tr>

  203.  * </table>

  204.  *

  205.  * <h3>Program Flow</h3>

  206.  *

  207.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  208.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  209.  * <tr class="TableRowColor"><td>Choose</td><td>Y</td></tr>

  210.  * <tr class="TableRowColor"><td>IIf</td><td>Y</td></tr>

  211.  * <tr class="TableRowColor"><td>Switch</td><td>Y</td></tr>

  212.  * </table>

  213.  *

  214.  * <h3>Text</h3>

  215.  *

  216.  * <table border="1" width="25%" cellpadding="3" cellspacing="0">

  217.  * <tr class="TableHeadingColor" align="left"><th>Function</th><th>Supported</th></tr>

  218.  * <tr class="TableRowColor"><td>Format[$]</td><td></td></tr>

  219.  * <tr class="TableRowColor"><td>InStr</td><td>Y</td></tr>

  220.  * <tr class="TableRowColor"><td>InStrRev</td><td>Y</td></tr>

  221.  * <tr class="TableRowColor"><td>LCase[$]</td><td>Y</td></tr>

  222.  * <tr class="TableRowColor"><td>Left[$]</td><td>Y</td></tr>

  223.  * <tr class="TableRowColor"><td>Len</td><td>Y</td></tr>

  224.  * <tr class="TableRowColor"><td>LTrim[$]</td><td>Y</td></tr>

  225.  * <tr class="TableRowColor"><td>RTrim[$]</td><td>Y</td></tr>

  226.  * <tr class="TableRowColor"><td>Trim[$]</td><td>Y</td></tr>

  227.  * <tr class="TableRowColor"><td>Mid[$]</td><td>Y</td></tr>

  228.  * <tr class="TableRowColor"><td>Replace</td><td>Y</td></tr>

  229.  * <tr class="TableRowColor"><td>Right[$]</td><td>Y</td></tr>

  230.  * <tr class="TableRowColor"><td>Space[$]</td><td>Y</td></tr>

  231.  * <tr class="TableRowColor"><td>StrComp</td><td>Y</td></tr>

  232.  * <tr class="TableRowColor"><td>StrConv[$]</td><td>Partial</td></tr>

  233.  * <tr class="TableRowColor"><td>String[$]</td><td>Y</td></tr>

  234.  * <tr class="TableRowColor"><td>StrReverse</td><td>Y</td></tr>

  235.  * <tr class="TableRowColor"><td>UCase[$]</td><td>Y</td></tr>

  236.  * </table>

  237.  *

  238.  *

  239.  *

  240.  */

  241. package com.healthmarketscience.jackcess.expr;