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author | Matthew Wild <mwild1@gmail.com> | 2015-05-19 16:33:18 +0100 |
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committer | Matthew Wild <mwild1@gmail.com> | 2015-05-19 16:33:18 +0100 |
commit | 25aa5f3bb97650283386799a4bf8b36012aeacdf (patch) | |
tree | 14a722959d1179338adec58efd9e5d7fcfa58ada /util | |
parent | ebe83d27d3179fa5d3c1452a8633a49d85a94f60 (diff) | |
parent | 98d695f3a199cdf07d26f9c0ae7d23a56da157a1 (diff) | |
download | prosody-25aa5f3bb97650283386799a4bf8b36012aeacdf.tar.gz prosody-25aa5f3bb97650283386799a4bf8b36012aeacdf.zip |
Merge with trunk
Diffstat (limited to 'util')
-rw-r--r-- | util/interpolation.lua | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/util/interpolation.lua b/util/interpolation.lua new file mode 100644 index 00000000..b78bdfd1 --- /dev/null +++ b/util/interpolation.lua @@ -0,0 +1,77 @@ +-- Simple template language +-- +-- The new() function takes a pattern and an escape function and returns +-- a render() function. Both are required. +-- +-- The function render() takes a string template and a table of values. +-- Sequences like {name} in the template string are substituted +-- with values from the table, optionally depending on a modifier +-- symbol. +-- +-- Variants are: +-- {name} is substituted for values["name"] and is escaped using the +-- second argument to new_render(). To disable the escaping, use {name!}. +-- {name.item} can be used to access table items. +-- To renter lists of items: {name# item number {idx} is {item} } +-- Or key-value pairs: {name% t[ {idx} ] = {item} } +-- To show a defaults for missing values {name? sub-template } can be used, +-- which renders a sub-template if values["name"] is false-ish. +-- {name& sub-template } does the opposite, the sub-template is rendered +-- if the selected value is anything but false or nil. + +local type, tostring = type, tostring; +local pairs, ipairs = pairs, ipairs; +local s_sub, s_gsub, s_match = string.sub, string.gsub, string.match; +local t_concat = table.concat; + +local function new_render(pat, escape) + -- assert(type(pat) == "string", "bad argument #1 to 'new_render' (string expected)"); + -- assert(type(escape) == "function", "bad argument #2 to 'new_render' (function expected)"); + local function render(template, values) + -- assert(type(template) == "string", "bad argument #1 to 'render' (string expected)"); + -- assert(type(values) == "table", "bad argument #2 to 'render' (table expected)"); + return (s_gsub(template, pat, function (block) + block = s_sub(block, 2, -2); + local name, opt, e = s_match(block, "^([%a_][%w_.]*)(%p?)()"); + if not name then return end + local value = values[name]; + if not value and name:find(".", 2, true) then + value = values; + for word in name:gmatch"[^.]+" do + value = value[word]; + if not value then break; end + end + end + if opt == '#' or opt == '%' then + if type(value) ~= "table" then return ""; end + local iter = opt == '#' and ipairs or pairs; + local out, i, subtpl = {}, 1, s_sub(block, e); + local subvalues = setmetatable({}, { __index = values }); + for idx, item in iter(value) do + subvalues.idx = idx; + subvalues.item = item; + out[i], i = render(subtpl, subvalues), i+1; + end + return t_concat(out); + elseif opt == '&' then + if not value then return ""; end + return render(s_sub(block, e), values); + elseif opt == '?' and not value then + return render(s_sub(block, e), values); + elseif value ~= nil then + if type(value) ~= "string" then + value = tostring(value); + end + if opt ~= '!' then + return escape(value); + end + return value; + end + end)); + end + return render; +end + +return { + new = new_render; +}; |