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module ActionController
module Routing
# BEFORE: 0.191446860631307 ms/url
# AFTER: 0.029847304022858 ms/url
# Speed up: 6.4 times
#
# Route recognition is slow due to one-by-one iterating over
# a whole routeset (each map.resources generates at least 14 routes)
# and matching weird regexps on each step.
#
# We optimize this by skipping all URI segments that 100% sure can't
# be matched, moving deeper in a tree of routes (where node == segment)
# until first possible match is accured. In such case, we start walking
# a flat list of routes, matching them with accurate matcher.
# So, first step: search a segment tree for the first relevant index.
# Second step: iterate routes starting with that index.
#
# How tree is walked? We can do a recursive tests, but it's smarter:
# We just create a tree of if-s and elsif-s matching segments.
#
# We have segments of 3 flavors:
# 1) nil (no segment, route finished)
# 2) const-dot-dynamic (like "/posts.:xml", "/preview.:size.jpg")
# 3) const (like "/posts", "/comments")
# 4) dynamic ("/:id", "file.:size.:extension")
#
# We split incoming string into segments and iterate over them.
# When segment is nil, we drop immediately, on a current node index.
# When segment is equal to some const, we step into branch.
# If none constants matched, we step into 'dynamic' branch (it's a last).
# If we can't match anything, we drop to last index on a level.
#
# Note: we maintain the original routes order, so we finish building
# steps on a first dynamic segment.
#
#
# Example. Given the routes:
# 0 /posts/
# 1 /posts/:id
# 2 /posts/:id/comments
# 3 /posts/blah
# 4 /users/
# 5 /users/:id
# 6 /users/:id/profile
#
# request_uri = /users/123
#
# There will be only 4 iterations:
# 1) segm test for /posts prefix, skip all /posts/* routes
# 2) segm test for /users/
# 3) segm test for /users/:id
# (jump to list index = 5)
# 4) full test for /users/:id => here we are!
class RouteSet
def recognize_path(path, environment={})
result = recognize_optimized(path, environment) and return result
# Route was not recognized. Try to find out why (maybe wrong verb).
allows = HTTP_METHODS.select { |verb| routes.find { |r| r.recognize(path, :method => verb) } }
if environment[:method] && !HTTP_METHODS.include?(environment[:method])
raise NotImplemented.new(*allows)
elsif !allows.empty?
raise MethodNotAllowed.new(*allows)
else
raise RoutingError, "No route matches #{path.inspect} with #{environment.inspect}"
end
end
def recognize_optimized(path, env)
write_recognize_optimized
recognize_optimized(path, env)
end
def write_recognize_optimized
tree = segment_tree(routes)
body = generate_code(tree)
instance_eval %{
def recognize_optimized(path, env)
segments = to_plain_segments(path)
index = #{body}
return nil unless index
while index < routes.size
result = routes[index].recognize(path, env) and return result
index += 1
end
nil
end
}, __FILE__, __LINE__
end
def segment_tree(routes)
tree = [0]
i = -1
routes.each do |route|
i += 1
# not fast, but runs only once
segments = to_plain_segments(route.segments.inject("") { |str,s| str << s.to_s })
node = tree
segments.each do |seg|
seg = :dynamic if seg && seg[0] == ?:
node << [seg, [i]] if node.empty? || node[node.size - 1][0] != seg
node = node[node.size - 1][1]
end
end
tree
end
def generate_code(list, padding=' ', level = 0)
# a digit
return padding + "#{list[0]}\n" if list.size == 1 && !(Array === list[0])
body = padding + "(seg = segments[#{level}]; \n"
i = 0
was_nil = false
list.each do |item|
if Array === item
i += 1
start = (i == 1)
final = (i == list.size)
tag, sub = item
if tag == :dynamic
body += padding + "#{start ? 'if' : 'elsif'} true\n"
body += generate_code(sub, padding + " ", level + 1)
break
elsif tag == nil && !was_nil
was_nil = true
body += padding + "#{start ? 'if' : 'elsif'} seg.nil?\n"
body += generate_code(sub, padding + " ", level + 1)
else
body += padding + "#{start ? 'if' : 'elsif'} seg == '#{tag}'\n"
body += generate_code(sub, padding + " ", level + 1)
end
end
end
body += padding + "else\n"
body += padding + " #{list[0]}\n"
body += padding + "end)\n"
body
end
# this must be really fast
def to_plain_segments(str)
str = str.dup
str.sub!(/^\/+/,'')
str.sub!(/\/+$/,'')
segments = str.split(/\.[^\/]+\/+|\/+|\.[^\/]+\Z/) # cut off ".format" also
segments << nil
segments
end
end
end
end
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