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Diffstat (limited to 'docs/design/alt.design/propertyExpressions.xml')
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1 files changed, 278 insertions, 278 deletions
diff --git a/docs/design/alt.design/propertyExpressions.xml b/docs/design/alt.design/propertyExpressions.xml index 0900a323a..7ebbcd4fe 100644 --- a/docs/design/alt.design/propertyExpressions.xml +++ b/docs/design/alt.design/propertyExpressions.xml @@ -15,214 +15,214 @@ <!-- one of (anchor s1) --> <s1 title="Property expression parsing"> <note> - The following discussion of the experiments with alternate - property expression parsing is very much a work in progress, - and subject to sudden changes. + The following discussion of the experiments with alternate + property expression parsing is very much a work in progress, + and subject to sudden changes. </note> <p> - The parsing of property value expressions is handled by two - closely related classes: <code>PropertyTokenizer</code> and its - subclass, <code>PropertyParser</code>. - <code>PropertyTokenizer</code>, as the name suggests, handles - the tokenizing of the expression, handing <em>tokens</em> - back to its subclass, - <code>PropertyParser</code>. <code>PropertyParser</code>, in - turn, returns a <code>PropertyValueList</code>, a list of - <code>PropertyValue</code>s. + The parsing of property value expressions is handled by two + closely related classes: <code>PropertyTokenizer</code> and its + subclass, <code>PropertyParser</code>. + <code>PropertyTokenizer</code>, as the name suggests, handles + the tokenizing of the expression, handing <em>tokens</em> + back to its subclass, + <code>PropertyParser</code>. <code>PropertyParser</code>, in + turn, returns a <code>PropertyValueList</code>, a list of + <code>PropertyValue</code>s. </p> <p> - The tokenizer and parser rely in turn on the datatype - definition from the <code>org.apache.fop.datatypes</code> - package and the datatype <code>static final int</code> - constants from <code>PropertyConsts</code>. + The tokenizer and parser rely in turn on the datatype + definition from the <code>org.apache.fop.datatypes</code> + package and the datatype <code>static final int</code> + constants from <code>PropertyConsts</code>. </p> <s2 title="Data types"> - <p> - The data types currently defined in - <code>org.apache.fop.datatypes</code> include: - </p> - <table> - <tr><th colspan="2">Numbers and lengths</th></tr> - <tr> - <th>Numeric</th> - <td colspan="3"> - The fundamental numeric data type. <em>Numerics</em> of - various types are constructed by the classes listed - below. - </td> - </tr> - <tr> - <td/> - <th colspan="3">Constructor classes for <em>Numeric</em></th> - </tr> - <tr> - <td/><td>Angle</td> - <td colspan="2">In degrees(deg), gradients(grad) or - radians(rad)</td> - </tr> - <tr> - <td/><td>Ems</td> - <td colspan="2">Relative length in <em>ems</em></td> - </tr> - <tr> - <td/><td>Frequency</td> - <td colspan="2">In hertz(Hz) or kilohertz(kHz)</td> - </tr> - <tr> - <td/><td>IntegerType</td><td/> - </tr> - <tr> - <td/><td>Length</td> - <td colspan="2">In centimetres(cm), millimetres(mm), - inches(in), points(pt), picas(pc) or pixels(px)</td> - </tr> - <tr> - <td/><td>Percentage</td><td/> - </tr> - <tr> - <td/><td>Time</td> - <td>In seconds(s) or milliseconds(ms)</td> - </tr> - <tr><th colspan="2">Strings</th></tr> - <tr> - <th>StringType</th> - <td colspan="3"> - Base class for data types which result in a <em>String</em>. - </td> - </tr> - <tr> - <td/><th>Literal</th> - <td colspan="2"> - A subclass of <em>StringType</em> for literals which - exceed the constraints of an <em>NCName</em>. - </td> - </tr> - <tr> - <td/><th>MimeType</th> - <td colspan="2"> - A subclass of <em>StringType</em> for literals which - represent a mime type. - </td> - </tr> - <tr> - <td/><th>UriType</th> - <td colspan="2"> - A subclass of <em>StringType</em> for literals which - represent a URI, as specified by the argument to - <em>url()</em>. - </td> - </tr> - <tr> - <td/><th>NCName</th> - <td colspan="2"> - A subclass of <em>StringType</em> for literals which - meet the constraints of an <em>NCName</em>. - </td> - </tr> - <tr> - <td/><td/><th>Country</th> - <td>An RFC 3066/ISO 3166 country code.</td> - </tr> - <tr> - <td/><td/><th>Language</th> - <td>An RFC 3066/ISO 639 language code.</td> - </tr> - <tr> - <td/><td/><th>Script</th> - <td>An ISO 15924 script code.</td> - </tr> - <tr><th colspan="2">Enumerated types</th></tr> - <tr> - <th>EnumType</th> - <td colspan="3"> - An integer representing one of the tokens in a set of - enumeration values. - </td> - </tr> - <tr> - <td/><th>MappedEnumType</th> - <td colspan="2"> - A subclass of <em>EnumType</em>. Maintains a - <em>String</em> with the value to which the associated - "raw" enumeration token maps. E.g., the - <em>font-size</em> enumeration value "medium" maps to - the <em>String</em> "12pt". - </td> - </tr> - <tr><th colspan="2">Colors</th></tr> - <tr> - <th>ColorType</th> - <td colspan="3"> - Maintains a four-element array of float, derived from - the name of a standard colour, the name returned by a - call to <em>system-color()</em>, or an RGB - specification. - </td> - </tr> - <tr><th colspan="2">Fonts</th></tr> - <tr> - <th>FontFamilySet</th> - <td colspan="3"> - Maintains an array of <em>String</em>s containing a - prioritized list of possibly generic font family names. - </td> - </tr> - <tr><th colspan="2">Pseudo-types</th></tr> - <tr> - <td colspan="4"> - A variety of pseudo-types have been defined as - convenience types for frequently appearing enumeration - token values, or for other special purposes. - </td> - </tr> - <tr> - <th>Inherit</th> - <td colspan="3"> - For values of <em>inherit</em>. - </td> - </tr> - <tr> - <th>Auto</th> - <td colspan="3"> - For values of <em>auto</em>. - </td> - </tr> - <tr> - <th>None</th> - <td colspan="3"> - For values of <em>none</em>. - </td> - </tr> - <tr> - <th>Bool</th> - <td colspan="3"> - For values of <em>true/false</em>. - </td> - </tr> - <tr> - <th>FromNearestSpecified</th> - <td colspan="3"> - Created to ensure that, when associated with - a shorthand, the <em>from-nearest-specified-value()</em> - core function is the sole component of the expression. - </td> - </tr> - <tr> - <th>FromParent</th> - <td colspan="3"> - Created to ensure that, when associated with - a shorthand, the <em>from-parent()</em> - core function is the sole component of the expression. - </td> - </tr> - </table> + <p> + The data types currently defined in + <code>org.apache.fop.datatypes</code> include: + </p> + <table> + <tr><th colspan="2">Numbers and lengths</th></tr> + <tr> + <th>Numeric</th> + <td colspan="3"> + The fundamental numeric data type. <em>Numerics</em> of + various types are constructed by the classes listed + below. + </td> + </tr> + <tr> + <td/> + <th colspan="3">Constructor classes for <em>Numeric</em></th> + </tr> + <tr> + <td/><td>Angle</td> + <td colspan="2">In degrees(deg), gradients(grad) or + radians(rad)</td> + </tr> + <tr> + <td/><td>Ems</td> + <td colspan="2">Relative length in <em>ems</em></td> + </tr> + <tr> + <td/><td>Frequency</td> + <td colspan="2">In hertz(Hz) or kilohertz(kHz)</td> + </tr> + <tr> + <td/><td>IntegerType</td><td/> + </tr> + <tr> + <td/><td>Length</td> + <td colspan="2">In centimetres(cm), millimetres(mm), + inches(in), points(pt), picas(pc) or pixels(px)</td> + </tr> + <tr> + <td/><td>Percentage</td><td/> + </tr> + <tr> + <td/><td>Time</td> + <td>In seconds(s) or milliseconds(ms)</td> + </tr> + <tr><th colspan="2">Strings</th></tr> + <tr> + <th>StringType</th> + <td colspan="3"> + Base class for data types which result in a <em>String</em>. + </td> + </tr> + <tr> + <td/><th>Literal</th> + <td colspan="2"> + A subclass of <em>StringType</em> for literals which + exceed the constraints of an <em>NCName</em>. + </td> + </tr> + <tr> + <td/><th>MimeType</th> + <td colspan="2"> + A subclass of <em>StringType</em> for literals which + represent a mime type. + </td> + </tr> + <tr> + <td/><th>UriType</th> + <td colspan="2"> + A subclass of <em>StringType</em> for literals which + represent a URI, as specified by the argument to + <em>url()</em>. + </td> + </tr> + <tr> + <td/><th>NCName</th> + <td colspan="2"> + A subclass of <em>StringType</em> for literals which + meet the constraints of an <em>NCName</em>. + </td> + </tr> + <tr> + <td/><td/><th>Country</th> + <td>An RFC 3066/ISO 3166 country code.</td> + </tr> + <tr> + <td/><td/><th>Language</th> + <td>An RFC 3066/ISO 639 language code.</td> + </tr> + <tr> + <td/><td/><th>Script</th> + <td>An ISO 15924 script code.</td> + </tr> + <tr><th colspan="2">Enumerated types</th></tr> + <tr> + <th>EnumType</th> + <td colspan="3"> + An integer representing one of the tokens in a set of + enumeration values. + </td> + </tr> + <tr> + <td/><th>MappedEnumType</th> + <td colspan="2"> + A subclass of <em>EnumType</em>. Maintains a + <em>String</em> with the value to which the associated + "raw" enumeration token maps. E.g., the + <em>font-size</em> enumeration value "medium" maps to + the <em>String</em> "12pt". + </td> + </tr> + <tr><th colspan="2">Colors</th></tr> + <tr> + <th>ColorType</th> + <td colspan="3"> + Maintains a four-element array of float, derived from + the name of a standard colour, the name returned by a + call to <em>system-color()</em>, or an RGB + specification. + </td> + </tr> + <tr><th colspan="2">Fonts</th></tr> + <tr> + <th>FontFamilySet</th> + <td colspan="3"> + Maintains an array of <em>String</em>s containing a + prioritized list of possibly generic font family names. + </td> + </tr> + <tr><th colspan="2">Pseudo-types</th></tr> + <tr> + <td colspan="4"> + A variety of pseudo-types have been defined as + convenience types for frequently appearing enumeration + token values, or for other special purposes. + </td> + </tr> + <tr> + <th>Inherit</th> + <td colspan="3"> + For values of <em>inherit</em>. + </td> + </tr> + <tr> + <th>Auto</th> + <td colspan="3"> + For values of <em>auto</em>. + </td> + </tr> + <tr> + <th>None</th> + <td colspan="3"> + For values of <em>none</em>. + </td> + </tr> + <tr> + <th>Bool</th> + <td colspan="3"> + For values of <em>true/false</em>. + </td> + </tr> + <tr> + <th>FromNearestSpecified</th> + <td colspan="3"> + Created to ensure that, when associated with + a shorthand, the <em>from-nearest-specified-value()</em> + core function is the sole component of the expression. + </td> + </tr> + <tr> + <th>FromParent</th> + <td colspan="3"> + Created to ensure that, when associated with + a shorthand, the <em>from-parent()</em> + core function is the sole component of the expression. + </td> + </tr> + </table> </s2> <s2 title="Tokenizer"> - <p> - The tokenizer returns one of the following token - values: - </p> - <source> + <p> + The tokenizer returns one of the following token + values: + </p> + <source> static final int EOF = 0 ,NCNAME = 1 @@ -255,86 +255,86 @@ // never set as the end result of parsing a token. ,NO_UNIT = 27 ; - </source> - <p> - Most of these tokens are self-explanatory, but a few need - further comment. - </p> - <dl> - <dt>AUTO</dt> - <dd> - Because of its frequency of occurrence, and the fact that - it is always the <em>initial value</em> for any property - which supports it, AUTO has been promoted into a - pseudo-type with its on datatype class. Therefore, it is - also reported as a token. - </dd> - <dt>NONE</dt> - <dd> - Similarly to AUTO, NONE has been promoted to a pseudo-type - because of its frequency. - </dd> - <dt>BOOL</dt> - <dd> - There is a <em>de facto</em> boolean type buried in the - enumeration types for many of the properties. It had been - specified as a type in its own right in this code. - </dd> - <dt>MIMETYPE</dt> - <dd> - The property <code>content-type</code> introduces this - complication. It can have two values of the form - <strong>content-type:</strong><em>mime-type</em> - (e.g. <code>content-type="content-type:xml/svg"</code>) or - <strong>namespace-prefix:</strong><em>prefix</em> - (e.g. <code>content-type="namespace-prefix:svg"</code>). The - experimental code reduces these options to the payload - in each case: an <code>NCName</code> in the case of a - namespace prefix, and a MIMETYPE in the case of a - content-type specification. <code>NCName</code>s cannot - contain a "/". - </dd> - </dl> + </source> + <p> + Most of these tokens are self-explanatory, but a few need + further comment. + </p> + <dl> + <dt>AUTO</dt> + <dd> + Because of its frequency of occurrence, and the fact that + it is always the <em>initial value</em> for any property + which supports it, AUTO has been promoted into a + pseudo-type with its on datatype class. Therefore, it is + also reported as a token. + </dd> + <dt>NONE</dt> + <dd> + Similarly to AUTO, NONE has been promoted to a pseudo-type + because of its frequency. + </dd> + <dt>BOOL</dt> + <dd> + There is a <em>de facto</em> boolean type buried in the + enumeration types for many of the properties. It had been + specified as a type in its own right in this code. + </dd> + <dt>MIMETYPE</dt> + <dd> + The property <code>content-type</code> introduces this + complication. It can have two values of the form + <strong>content-type:</strong><em>mime-type</em> + (e.g. <code>content-type="content-type:xml/svg"</code>) or + <strong>namespace-prefix:</strong><em>prefix</em> + (e.g. <code>content-type="namespace-prefix:svg"</code>). The + experimental code reduces these options to the payload + in each case: an <code>NCName</code> in the case of a + namespace prefix, and a MIMETYPE in the case of a + content-type specification. <code>NCName</code>s cannot + contain a "/". + </dd> + </dl> </s2> <s2 title="Parser"> - <p> - The parser retuns a <code>PropertyValueList</code>, - necessary because of the possibility that a list of - <code>PropertyValue</code> elements may be returned from the - expressions of soem properties. - </p> - <p> - <code>PropertyValueList</code>s may contain - <code>PropertyValue</code>s or other - <code>PropertyValueList</code>s. This latter provision is - necessitated for the peculiar case of of - <em>text-shadow</em>, which may contain whitespace separated - sublists of either two or three elements, separated from one - another by commas. To accommodate this peculiarity, comma - separated elements are added to the top-level list, while - whitespace separated values are always collected into - sublists to be added to the top-level list. - </p> - <p> - Other special cases include the processing of the core - functions <code>from-parent()</code> and - <code>from-nearest-specified-value()</code> when these - function calls are assigned to a shorthand property, or used - with a shorthand property name as an argument. In these - cases, the function call must be the sole component of the - expression. The pseudo-element classes - <code>FromParent</code> and - <code>FromNearestSpecified</code> are generated in these - circumstances so that an exception will be thrown if they - are involved in expression evaluation with other - components. (See Rec. Section 5.10.4 Property Value - Functions.) - </p> - <p> - The experimental code is a simple extension of the existing - parser code, which itself borrowed heavily from James - Clark's XT processor. - </p> + <p> + The parser retuns a <code>PropertyValueList</code>, + necessary because of the possibility that a list of + <code>PropertyValue</code> elements may be returned from the + expressions of soem properties. + </p> + <p> + <code>PropertyValueList</code>s may contain + <code>PropertyValue</code>s or other + <code>PropertyValueList</code>s. This latter provision is + necessitated for the peculiar case of of + <em>text-shadow</em>, which may contain whitespace separated + sublists of either two or three elements, separated from one + another by commas. To accommodate this peculiarity, comma + separated elements are added to the top-level list, while + whitespace separated values are always collected into + sublists to be added to the top-level list. + </p> + <p> + Other special cases include the processing of the core + functions <code>from-parent()</code> and + <code>from-nearest-specified-value()</code> when these + function calls are assigned to a shorthand property, or used + with a shorthand property name as an argument. In these + cases, the function call must be the sole component of the + expression. The pseudo-element classes + <code>FromParent</code> and + <code>FromNearestSpecified</code> are generated in these + circumstances so that an exception will be thrown if they + are involved in expression evaluation with other + components. (See Rec. Section 5.10.4 Property Value + Functions.) + </p> + <p> + The experimental code is a simple extension of the existing + parser code, which itself borrowed heavily from James + Clark's XT processor. + </p> </s2> </s1> </body> |