Rough description of how one might do multiPageTagLib

MultiPaginateTagLib.groovy

Closure paginate = { attrs ->

        // define new prefix aware keys
        def _sort = attrs.prefix? attrs.prefix +"_sort" : 'sort'
        def _offset = attrs.prefix? attrs.prefix + "_offset" : "offset"
        def _total = attrs.prefix? attrs.prefix + "_total" : "total"
        
        
        def writer = out
        if (attrs.total == null) {
            throwTagError("Tag [paginate] is missing required attribute [total]")
        }

        def messageSource = grailsAttributes.messageSource
        def locale = RCU.getLocale(request)

        def total = attrs.int(_total) ?: 0
        def action = (attrs.action ? attrs.action : (params.action ? params.action : "list"))
        def offset = params.int(_offset) ?: 0
        def max = params.int(_max)
        def maxsteps = (attrs.int(_maxsteps) ?: 10)

        if (!offset) offset = (attrs.int(_offset) ?: 0)
        if (!max) max = (attrs.int(_max) ?: 10)

        def linkParams = [:]
        if (attrs.params) linkParams.putAll(attrs.params)
        linkParams[_offset] = offset - max
        linkParams[_max] = max
        if (params[_sort]) linkParams[_sort] = params[_sort]
        if (params[_order]) linkParams[_order] = params[_order]

        def linkTagAttrs = [action: action]
        if (attrs.controller) {
            linkTagAttrs.controller = attrs.controller
        }
        if (attrs.id != null) {
            linkTagAttrs.id = attrs.id
        }
        if (attrs.fragment != null) {
            linkTagAttrs.fragment = attrs.fragment
        }
        linkTagAttrs.params = linkParams

        // determine paging variables
        def steps = maxsteps > 0
        int currentstep = (offset / max) + 1
        int firststep = 1
        int laststep = Math.round(Math.ceil(total / max))

        // display previous link when not on firststep
        if (currentstep > firststep) {
            linkTagAttrs.class = 'prevLink'
            linkParams.offset = offset - max
            writer << link(linkTagAttrs.clone()) {
                (attrs.prev ?: messageSource.getMessage('paginate.prev', null, messageSource.getMessage('default.paginate.prev', null, 'Previous', locale), locale))
            }
        }

        // display steps when steps are enabled and laststep is not firststep
        if (steps && laststep > firststep) {
            linkTagAttrs.class = 'step'

            // determine begin and endstep paging variables
            int beginstep = currentstep - Math.round(maxsteps / 2) + (maxsteps % 2)
            int endstep = currentstep + Math.round(maxsteps / 2) - 1

            if (beginstep < firststep) {
                beginstep = firststep
                endstep = maxsteps
            }
            if (endstep > laststep) {
                beginstep = laststep - maxsteps + 1
                if (beginstep < firststep) {
                    beginstep = firststep
                }
                endstep = laststep
            }

            // display firststep link when beginstep is not firststep
            if (beginstep > firststep) {
                linkParams.offset = 0
                writer << link(linkTagAttrs.clone()) {firststep.toString()}
                writer << '<span class="step">..</span>'
            }

            // display paginate steps
            (beginstep..endstep).each { i ->
                if (currentstep == i) {
                    writer << "<span class=\"currentStep\">${i}</span>"
                }
                else {
                    linkParams.offset = (i - 1) * max
                    writer << link(linkTagAttrs.clone()) {i.toString()}
                }
            }

            // display laststep link when endstep is not laststep
            if (endstep < laststep) {
                writer << '<span class="step">..</span>'
                linkParams.offset = (laststep - 1) * max
                writer << link(linkTagAttrs.clone()) { laststep.toString() }
            }
        }

        // display next link when not on laststep
        if (currentstep < laststep) {
            linkTagAttrs.class = 'nextLink'
            linkParams.offset = offset + max
            writer << link(linkTagAttrs.clone()) {
                (attrs.next ? attrs.next : messageSource.getMessage('paginate.next', null, messageSource.getMessage('default.paginate.next', null, 'Next', locale), locale))
            }
        }
    }