[xsl] How to do this tricky elimination on XML using XSLT ?

[Jo Na <jkoe888@xxxxxxxxx>]

Hi,
I have this input xml:
    <map>
        <region>
            <gridA id="1">
                <blockA id="01" method="build">
                    <building1 id="x" method="build">
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be removed -->
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="01">
                    <building1 id="x" method="modify">
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be kept (prev node have same id but diff method so it's not
considered as successive -->
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="02">
                    <building3 id="y" method="modify">
                        <otherchild>b</otherchild>
                    </building3>
                    <building2 id="x" method="demolish"/>
                </blockA>

                <blockA id="01">
                    <building1 id="y" method="build"> <!-- this one
will be kept (diff id) -->
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be removed -->
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="02">
                    <building3 id="y" method="modify"> <!-- this one
will be removed -->
                        <otherchild>b</otherchild>
                    </building3>
                    <building2 id="x" method="demolish"/> <!-- this
one will be removed -->
                </blockA>
            </gridA>

            <gridA id="2">
                <blockA id="01" method="build">
                    <building1 id="x" method="build">
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be removed -->
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be kept (diff children) -->
                        <otherchild>b</otherchild>
                    </building1>
                </blockA>
                <blockA id="01">
                    <building1 id="x" method="build"> <!-- this one
will be removed -->
                        <otherchild>b</otherchild>
                    </building1>
                </blockA>
            </gridA>
            <gridB id="1">
                ...and so on..
            </gridB>
        </region>
    </map>

Expected Output:

    <map>
        <region>
            <gridA id="1">
                <blockA id="01" method="build">
                    <building1 id="x" method="build">
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="01">
                    <building1 id="x" method="modify">
                        <otherchild>a</otherchild>
                    </building1>
                    <building1 id="x" method="build"> <!-- this one
will be kept (prev node have same id but diff method so it's not
considered as successive -->
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="02">
                    <building3 id="y" method="modify">
                        <otherchild>b</otherchild>
                    </building3>
                    <building2 id="x" method="demolish"/>
                </blockA>

                <blockA id="01">
                    <building1 id="y" method="build"> <!-- this one
will be kept (diff id) -->
                        <otherchild>a</otherchild>
                    </building1>
                </blockA>

                <blockA id="02"/>
            </gridA>

            <gridA id="2">
                <blockA id="01" method="build">
                    <building1 id="x" method="build">
                        <otherchild>a</otherchild>
                    </building1>

                    <building1 id="x" method="build"> <!-- this one
will be kept (diff children) -->
                        <otherchild>b</otherchild>
                    </building1>
                </blockA>
                <blockA id="01"/>
            </gridA>
            <gridB id="1">
                ...and so on..
            </gridB>
        </region>
    </map>
The XSLT so far:

    <xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
        <xsl:output indent="yes"/> <xsl:strip-space elements="*"/>

        <xsl:template match="node()|@*">
            <xsl:copy>
                <xsl:apply-templates select="node()|@*"/>
            </xsl:copy>
        </xsl:template>

        <xsl:template match="region/*/*/*
             [deep-equal(.,preceding::*[name()=current()/name()]
                           [@id = current()/@id]
                           [../../@id = current()/../../@id][1])]" />
    </xsl:stylesheet>

the problem with the XSLT right now is that it cannot differentiate
duplicates that happens in siblings (i.e blockA with the same id).

I need to remove a node that are considered as *repetitive*.

**Two node that have the same `name` and `id` will be considered
*repetitive* if it appears one after another and it has the same
`method` and `children`.**

**for example:**

    <elem id="1" method="a" />
    <elem id="1" method="a" /> <!-- this is repetitive for id=1-->
    <elem id="1" method="b" />
    <elem id="1" method="a" /> <!-- this is the new boundary for removal
id=1-->
    <elem id="2" method="a" />
    <elem id="1" method="a" /> <!-- this is repetitive for id=1 -->
    <elem id="2" method="a" /> <!-- this is repetitive for id=2 -->

**will be simplified into:**

    <elem id="1" method="a" />
    <elem id="1" method="b" />
    <elem id="1" method="a" /> <!-- this is the new boundary for removal
id=1-->
    <elem id="2" method="a" />

 **- Everytime a successive node with the `same id` has `different method`,
   the `boundary` for the next removal for that `id` is reset.**

 - we need to take into account duplicates that are under one parent
or siblings (two or more parents nodes that has the same element name
and id) i.e (in example: `blockX`)
 - if the two nodes being compared did not share the same `gridX`
level, then they should not be considered as duplicates to be removed

Please let me know how to achieve such transformation using XSLT.
Thanks very much for the help.