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if not modules then modules = { } end modules ['data-con'] = {
version = 1.001,
comment = "companion to luat-lib.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local format, lower, gsub = string.format, string.lower, string.gsub
local trace_cache = false trackers.register("resolvers.cache", function(v) trace_cache = v end)
local trace_containers = false trackers.register("resolvers.containers", function(v) trace_containers = v end)
local trace_storage = false trackers.register("resolvers.storage", function(v) trace_storage = v end)
--[[ldx--
<p>Once we found ourselves defining similar cache constructs
several times, containers were introduced. Containers are used
to collect tables in memory and reuse them when possible based
on (unique) hashes (to be provided by the calling function).</p>
<p>Caching to disk is disabled by default. Version numbers are
stored in the saved table which makes it possible to change the
table structures without bothering about the disk cache.</p>
<p>Examples of usage can be found in the font related code.</p>
--ldx]]--
containers = containers or { }
containers.usecache = true
local function report(container,tag,name)
if trace_cache or trace_containers then
logs.report(format("%s cache",container.subcategory),"%s: %s",tag,name or 'invalid')
end
end
local allocated = { }
-- tracing
function containers.define(category, subcategory, version, enabled)
return function()
if category and subcategory then
local c = allocated[category]
if not c then
c = { }
allocated[category] = c
end
local s = c[subcategory]
if not s then
s = {
category = category,
subcategory = subcategory,
storage = { },
enabled = enabled,
version = version or 1.000,
trace = false,
path = caches and caches.setpath and caches.setpath(category,subcategory),
}
c[subcategory] = s
end
return s
else
return nil
end
end
end
function containers.is_usable(container, name)
return container.enabled and caches and caches.iswritable(container.path, name)
end
function containers.is_valid(container, name)
if name and name ~= "" then
local storage = container.storage[name]
return storage and not table.is_empty(storage) and storage.cache_version == container.version
else
return false
end
end
function containers.read(container,name)
if container.enabled and caches and not container.storage[name] and containers.usecache then
container.storage[name] = caches.loaddata(container.path,name)
if containers.is_valid(container,name) then
report(container,"loaded",name)
else
container.storage[name] = nil
end
end
if container.storage[name] then
report(container,"reusing",name)
end
return container.storage[name]
end
function containers.write(container, name, data)
if data then
data.cache_version = container.version
if container.enabled and caches then
local unique, shared = data.unique, data.shared
data.unique, data.shared = nil, nil
caches.savedata(container.path, name, data)
report(container,"saved",name)
data.unique, data.shared = unique, shared
end
report(container,"stored",name)
container.storage[name] = data
end
return data
end
function containers.content(container,name)
return container.storage[name]
end
function containers.cleanname(name)
return (gsub(lower(name),"[^%w%d]+","-"))
end
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