3 # Copyright 2004, 2005 by Jim Weirich (jim@weirichhouse.org).
6 # Permission is granted for use, copying, modification, distribution,
7 # and distribution of modified versions of this work as long as the
8 # above copyright notice is included.
11 # Provide a flexible and easy to use Builder for creating XML markup.
12 # See XmlBuilder for usage details.
14 require 'builder/xmlbase'
18 # Create XML markup easily. All (well, almost all) methods sent to
19 # an XmlMarkup object will be translated to the equivalent XML
20 # markup. Any method with a block will be treated as an XML markup
21 # tag with nested markup in the block.
23 # Examples will demonstrate this easier than words. In the
24 # following, +xm+ is an +XmlMarkup+ object.
26 # xm.em("emphasized") # => <em>emphasized</em>
27 # xm.em { xmm.b("emp & bold") } # => <em><b>emph & bold</b></em>
28 # xm.a("A Link", "href"=>"http://onestepback.org")
29 # # => <a href="http://onestepback.org">A Link</a>
30 # xm.div { br } # => <div><br/></div>
31 # xm.target("name"=>"compile", "option"=>"fast")
32 # # => <target option="fast" name="compile"\>
33 # # NOTE: order of attributes is not specified.
35 # xm.instruct! # <?xml version="1.0" encoding="UTF-8"?>
38 # xm.title("History") # <title>History</title>
41 # xm.h1("Header") # <h1>Header</h1>
42 # xm.p("paragraph") # <p>paragraph</p>
48 # * The order that attributes are inserted in markup tags is
51 # * Sometimes you wish to insert text without enclosing tags. Use
52 # the <tt>text!</tt> method to accomplish this.
57 # xm.text! "line"; xm.br # line<br/>
58 # xm.text! "another line"; xmbr # another line<br/>
61 # * The special XML characters <, >, and & are converted to <,
62 # > and & automatically. Use the <tt><<</tt> operation to
63 # insert text without modification.
65 # * Sometimes tags use special characters not allowed in ruby
66 # identifiers. Use the <tt>tag!</tt> method to handle these
71 # xml.tag!("SOAP:Envelope") { ... }
75 # <SOAP:Envelope> ... </SOAP:Envelope>"
77 # <tt>tag!</tt> will also take text and attribute arguments (after
78 # the tag name) like normal markup methods. (But see the next
79 # bullet item for a better way to handle XML namespaces).
81 # * Direct support for XML namespaces is now available. If the
82 # first argument to a tag call is a symbol, it will be joined to
83 # the tag to produce a namespace:tag combination. It is easier to
84 # show this than describe it.
86 # xml.SOAP :Envelope do ... end
88 # Just put a space before the colon in a namespace to produce the
89 # right form for builder (e.g. "<tt>SOAP:Envelope</tt>" =>
90 # "<tt>xml.SOAP :Envelope</tt>")
92 # * XmlMarkup builds the markup in any object (called a _target_)
93 # that accepts the <tt><<</tt> method. If no target is given,
94 # then XmlMarkup defaults to a string target.
98 # xm = Builder::XmlMarkup.new
99 # result = xm.title("yada")
100 # # result is a string containing the markup.
103 # xm = Builder::XmlMarkup.new(buffer)
104 # # The markup is appended to buffer (using <<)
106 # xm = Builder::XmlMarkup.new(STDOUT)
107 # # The markup is written to STDOUT (using <<)
109 # xm = Builder::XmlMarkup.new
110 # x2 = Builder::XmlMarkup.new(:target=>xm)
111 # # Markup written to +x2+ will be send to +xm+.
113 # * Indentation is enabled by providing the number of spaces to
114 # indent for each level as a second argument to XmlBuilder.new.
115 # Initial indentation may be specified using a third parameter.
119 # xm = Builder.new(:ident=>2)
120 # # xm will produce nicely formatted and indented XML.
122 # xm = Builder.new(:indent=>2, :margin=>4)
123 # # xm will produce nicely formatted and indented XML with 2
124 # # spaces per indent and an over all indentation level of 4.
126 # builder = Builder::XmlMarkup.new(:target=>$stdout, :indent=>2)
127 # builder.name { |b| b.first("Jim"); b.last("Weirich) }
130 # # <first>Jim</first>
131 # # <last>Weirich</last>
134 # * The instance_eval implementation which forces self to refer to
135 # the message receiver as self is now obsolete. We now use normal
136 # block calls to execute the markup block. This means that all
137 # markup methods must now be explicitly send to the xml builder.
138 # For instance, instead of
140 # xml.div { strong("text") }
144 # xml.div { xml.strong("text") }
146 # Although more verbose, the subtle change in semantics within the
147 # block was found to be prone to error. To make this change a
148 # little less cumbersome, the markup block now gets the markup
149 # object sent as an argument, allowing you to use a shorter alias
154 # xml_builder = Builder::XmlMarkup.new
155 # xml_builder.div { |xml|
159 class XmlMarkup < XmlBase
161 # Create an XML markup builder. Parameters are specified by an
164 # :target=><em>target_object</em>::
165 # Object receiving the markup. +out+ must respond to the
166 # <tt><<</tt> operator. The default is a plain string target.
168 # :indent=><em>indentation</em>::
169 # Number of spaces used for indentation. The default is no
170 # indentation and no line breaks.
172 # :margin=><em>initial_indentation_level</em>::
173 # Amount of initial indentation (specified in levels, not
176 # :escape_attrs=><b>OBSOLETE</em>::
177 # The :escape_attrs option is no longer supported by builder
178 # (and will be quietly ignored). String attribute values are
179 # now automatically escaped. If you need unescaped attribute
180 # values (perhaps you are using entities in the attribute
181 # values), then give the value as a Symbol. This allows much
182 # finer control over escaping attribute values.
184 def initialize(options={})
185 indent = options[:indent] || 0
186 margin = options[:margin] || 0
187 super(indent, margin)
188 @target = options[:target] || ""
191 # Return the target of the builder.
196 def comment!(comment_text)
197 _ensure_no_block block_given?
198 _special("<!-- ", " -->", comment_text, nil)
201 # Insert an XML declaration into the XML markup.
205 # xml.declare! :ELEMENT, :blah, "yada"
206 # # => <!ELEMENT blah "yada">
207 def declare!(inst, *args, &block)
209 @target << "<!#{inst}"
213 @target << %{ "#{arg}"}
221 _nested_structures(block)
228 # Insert a processing instruction into the XML markup. E.g.
233 # #=> <?xml version="1.0" encoding="UTF-8"?>
234 # xml.instruct! :aaa, :bbb=>"ccc"
235 # #=> <?aaa bbb="ccc"?>
237 def instruct!(directive_tag=:xml, attrs={})
238 _ensure_no_block block_given?
239 if directive_tag == :xml
240 a = { :version=>"1.0", :encoding=>"UTF-8" }
241 attrs = a.merge attrs
244 "<?#{directive_tag}",
248 [:version, :encoding, :standalone])
251 # Insert a CDATA section into the XML markup.
255 # xml.cdata!("text to be included in cdata")
256 # #=> <![CDATA[text to be included in cdata]]>
259 _ensure_no_block block_given?
260 _special("<![CDATA[", "]]>", text, nil)
265 # NOTE: All private methods of a builder object are prefixed when
266 # a "_" character to avoid possible conflict with XML tag names.
268 # Insert text directly in to the builder's target.
273 # Insert special instruction.
274 def _special(open, close, data=nil, attrs=nil, order=[])
277 @target << data if data
278 _insert_attributes(attrs, order) if attrs
283 # Start an XML tag. If <tt>end_too</tt> is true, then the start
284 # tag is also the end tag (e.g. <br/>
285 def _start_tag(sym, attrs, end_too=false)
287 _insert_attributes(attrs)
288 @target << "/" if end_too
292 # Insert an ending tag.
294 @target << "</#{sym}>"
297 # Insert the attributes (given in the hash).
298 def _insert_attributes(attrs, order=[])
302 @target << %{ #{k}="#{_attr_value(v)}"} if v
305 @target << %{ #{k}="#{_attr_value(v)}"} unless order.member?(k)
309 def _attr_value(value)
314 _escape_quote(value.to_s)
318 def _ensure_no_block(got_block)
320 fail IllegalBlockError,
321 "Blocks are not allowed on XML instructions"