cre full text search: fix inconsistencies (#3656)

Fix various inconsitencies: some occurences not highlighted
on displayed page; different occurences highlighted on same
page wheter we went there searching backward or forward; pages
with occurences simply just skipped when searching in one
direction, and not in the other...
To avoid edge cases, crengine will now give back results on up
to 3 pages, that we need to filter.
Bump base and crengine

base

@@ -1 +1 @@
-Subproject commit 027cc1c648fa54ad637aee083527a671fad65df9
+Subproject commit 81cd9b5b9324de5f6039a1ccaf49f189ccce59ad

frontend/apps/reader/modules/readersearch.lua

@@ -7,6 +7,11 @@ local _ = require("gettext")
 local ReaderSearch = InputContainer:new{
     direction = 0, -- 0 for search forward, 1 for search backward
     case_insensitive = true, -- default to case insensitive
+
+    -- internal: whether we expect results on previous pages
+    -- (can be different from self.direction, if, from a page in the
+    -- middle of a book, we search forward from start of book)
+    _expect_back_results = false,
 }
 
 function ReaderSearch:init()
@@ -29,6 +34,7 @@ end
 
 function ReaderSearch:onShowSearchDialog(text)
     local neglect_current_location = false
+    local current_page
     local do_search = function(search_func, _text, param)
         return function()
             local res = search_func(self, _text, param)
@@ -37,7 +43,68 @@ function ReaderSearch:onShowSearchDialog(text)
                     self.ui.link:onGotoLink({page = res.page - 1}, neglect_current_location)
                     self.view.highlight.temp[res.page] = res
                 else
-                    self.ui.link:onGotoLink(res[1].start, neglect_current_location)
+                    -- Was previously just:
+                    --   self.ui.link:onGotoLink(res[1].start, neglect_current_location)
+
+                    -- To avoid problems with edge cases, crengine may now give us links
+                    -- that are on previous/next page of the page we should show. And
+                    -- sometimes even xpointers that resolve to no page.
+                    -- We need to loop thru all the results until we find one suitable,
+                    -- to follow its link and go to the next/prev page with occurences.
+                    local valid_link
+                    -- If backward search, results are already in a reversed order, so we'll
+                    -- start from the nearest to current page one.
+                    for _, r in ipairs(res) do
+                        -- result's start and end may be on different pages, we must
+                        -- consider both
+                        local r_start = r["start"]
+                        local r_end = r["end"]
+                        local r_start_page = self.ui.document:getPageFromXPointer(r_start)
+                        local r_end_page = self.ui.document:getPageFromXPointer(r_end)
+                        logger.dbg("res.start page & xpointer:", r_start_page, r_start)
+                        logger.dbg("res.end page & xpointer:", r_end_page, r_end)
+                        local bounds = {}
+                        if self._expect_back_results then
+                            -- Process end of occurence first, which is nearest to current page
+                            table.insert(bounds, {r_end, r_end_page})
+                            table.insert(bounds, {r_start, r_start_page})
+                        else
+                            table.insert(bounds, {r_start, r_start_page})
+                            table.insert(bounds, {r_end, r_end_page})
+                        end
+                        for _, b in ipairs(bounds) do
+                            local xpointer = b[1]
+                            local page = b[2]
+                            -- Look if it is valid for us
+                            if page then -- it should resolve to a page
+                                if not current_page then -- initial search
+                                    -- We can (and should if there are) display results on current page
+                                    current_page = self.ui.document:getCurrentPage()
+                                    if (self._expect_back_results and page <= current_page) or
+                                       (not self._expect_back_results and page >= current_page) then
+                                        valid_link = xpointer
+                                    end
+                                else -- subsequent searches
+                                    -- We must change page, so only consider results from
+                                    -- another page, in the adequate search direction
+                                    current_page = self.ui.document:getCurrentPage()
+                                    if (self._expect_back_results and page < current_page) or
+                                       (not self._expect_back_results and page > current_page) then
+                                        valid_link = xpointer
+                                    end
+                                end
+                            end
+                            if valid_link then
+                                break
+                            end
+                        end
+                        if valid_link then
+                            break
+                        end
+                    end
+                    if valid_link then
+                        self.ui.link:onGotoLink(valid_link, neglect_current_location)
+                    end
                 end
                 -- Don't add result pages to location ("Go back") stack
                 neglect_current_location = true
@@ -89,22 +156,26 @@ end
 
 function ReaderSearch:searchFromStart(pattern)
     self.direction = 0
+    self._expect_back_results = true
     return self:search(pattern, -1)
 end
 
 function ReaderSearch:searchFromEnd(pattern)
     self.direction = 1
+    self._expect_back_results = false
     return self:search(pattern, -1)
 end
 
 function ReaderSearch:searchFromCurrent(pattern, direction)
     self.direction = direction
+    self._expect_back_results = direction == 1
     return self:search(pattern, 0)
 end
 
 -- ignore current page and search next occurrence
 function ReaderSearch:searchNext(pattern, direction)
     self.direction = direction
+    self._expect_back_results = direction == 1
     return self:search(pattern, 1)
 end
 

spec/unit/readersearch_spec.lua

@@ -81,13 +81,29 @@ describe("Readersearch module", function()
         it("should find all occurrences", function()
             local count = 0
             rolling:onGotoPage(1)
+            local cur_page = doc:getCurrentPage()
             local words = search:searchFromCurrent("Verona", 0)
             while words do
-                count = count + #words
+                local new_page = nil
                 for _, word in ipairs(words) do
                     --dbg("found word", word.start)
+                    local word_page = doc:getPageFromXPointer(word.start)
+                    if word_page ~= cur_page then -- ignore words on current page
+                        if not new_page then -- first word on a new page
+                            new_page = word_page
+                            count = count + 1
+                            doc:gotoXPointer(word.start) -- go to this new page
+                        else -- new page seen
+                            if word_page == new_page then -- only count words on this new page
+                                count = count + 1
+                            end
+                        end
+                    end
+                end
+                if not new_page then -- no word seen on any new page
+                    break
                 end
-                doc:gotoXPointer(words[#words].start)
+                cur_page = doc:getCurrentPage()
                 words = search:searchNext("Verona", 0)
             end
             assert.are.equal(13, count)