diff options
Diffstat (limited to 'background_scripts/completion_search.coffee')
| -rw-r--r-- | background_scripts/completion_search.coffee | 78 |
1 files changed, 55 insertions, 23 deletions
diff --git a/background_scripts/completion_search.coffee b/background_scripts/completion_search.coffee index b26194e6..7926b45b 100644 --- a/background_scripts/completion_search.coffee +++ b/background_scripts/completion_search.coffee @@ -1,4 +1,39 @@ +# This is a wrapper class for completion engines. It handles the case where a custom search engine includes a +# prefix query term (or terms). For example: +# +# http://www.google.com/search?q=javascript+%s +# +# In this case, we get better suggestions if we include the term "javascript" in queries sent to the +# completion engine. This wrapper handles adding such prefixes to completion-engine queries and removing them +# from the resulting suggestions. +class EnginePrefixWrapper + constructor: (@searchUrl, @engine) -> + + getUrl: (queryTerms) -> + # This tests whether @searchUrl contains something of the form "...=abc+def+%s...", from which we extract + # a prefix of the form "abc def ". + if /\=.+\+%s/.test @searchUrl + terms = @searchUrl.replace /\+%s.*/, "" + terms = terms.replace /.*=/, "" + terms = terms.replace /\+/g, " " + + queryTerms = [ terms.split(" ")..., queryTerms... ] + prefix = "#{terms} " + + @postprocessSuggestions = + (suggestions) -> + for suggestion in suggestions + continue unless suggestion.startsWith prefix + suggestion[prefix.length..] + + @engine.getUrl queryTerms + + parse: (xhr) -> + @postprocessSuggestions @engine.parse xhr + + postprocessSuggestions: (suggestions) -> suggestions + CompletionSearch = debug: false inTransit: {} @@ -58,34 +93,30 @@ CompletionSearch = return callback [] if 1 == queryTerms.length and Utils.isUrl query return callback [] if Utils.hasJavascriptPrefix query - # Cache completions. However, completions depend upon both the searchUrl and the query terms. So we need - # to generate a key. We mix in some junk generated by pwgen. A key clash might be possible, but - # is vanishingly unlikely. - junk = "//Zi?ei5;o//" - completionCacheKey = searchUrl + junk + queryTerms.map((s) -> s.toLowerCase()).join junk - + completionCacheKey = JSON.stringify [ searchUrl, queryTerms ] if @completionCache.has completionCacheKey console.log "hit", completionCacheKey if @debug return callback @completionCache.get completionCacheKey # If the user appears to be typing a continuation of the characters of the most recent query, then we can # sometimes re-use the previous suggestions. - if @mostRecentQuery? and @mostRecentSuggestions? - reusePreviousSuggestions = do => - # Verify that the previous query is a prefix of the current query. - return false unless 0 == query.indexOf @mostRecentQuery.toLowerCase() - # Verify that every previous suggestion contains the text of the new query. - # Note: @mostRecentSuggestions may also be empty, in which case we drop though. The effect is that - # previous queries with no suggestions suppress subsequent no-hope HTTP requests as the user continues - # to type. - for suggestion in @mostRecentSuggestions - return false unless 0 <= suggestion.indexOf query - # Ok. Re-use the suggestion. - true - - if reusePreviousSuggestions - console.log "reuse previous query:", @mostRecentQuery, @mostRecentSuggestions.length if @debug - return callback @completionCache.set completionCacheKey, @mostRecentSuggestions + if @mostRecentQuery? and @mostRecentSuggestions? and @mostRecentSearchUrl? + if searchUrl == @mostRecentSearchUrl + reusePreviousSuggestions = do => + # Verify that the previous query is a prefix of the current query. + return false unless 0 == query.indexOf @mostRecentQuery.toLowerCase() + # Verify that every previous suggestion contains the text of the new query. + # Note: @mostRecentSuggestions may also be empty, in which case we drop though. The effect is that + # previous queries with no suggestions suppress subsequent no-hope HTTP requests as the user continues + # to type. + for suggestion in @mostRecentSuggestions + return false unless 0 <= suggestion.indexOf query + # Ok. Re-use the suggestion. + true + + if reusePreviousSuggestions + console.log "reuse previous query:", @mostRecentQuery, @mostRecentSuggestions.length if @debug + return callback @completionCache.set completionCacheKey, @mostRecentSuggestions # That's all of the caches we can try. Bail if the caller is only requesting synchronous results. We # signal that we haven't found a match by returning null. @@ -98,7 +129,7 @@ CompletionSearch = # Elide duplicate requests. First fetch the suggestions... @inTransit[completionCacheKey] ?= new AsyncDataFetcher (callback) => - engine = @lookupEngine searchUrl + engine = new EnginePrefixWrapper searchUrl, @lookupEngine searchUrl url = engine.getUrl queryTerms @get searchUrl, url, (xhr = null) => @@ -124,6 +155,7 @@ CompletionSearch = # ... then use the suggestions. @inTransit[completionCacheKey].use (suggestions) => + @mostRecentSearchUrl = searchUrl @mostRecentQuery = query @mostRecentSuggestions = suggestions callback @completionCache.set completionCacheKey, suggestions |