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util.xtemplate: Yet another string template library

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This one takes a stanza as input

Roughly based on util.interpolation
This commit is contained in:
Kim Alvefur 2022-01-24 23:54:32 +01:00
parent 55da054c9b
commit 7e65b1deef
2 changed files with 187 additions and 0 deletions
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101
teal-src/util/xtemplate.tl Normal file
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-- render(template, stanza) --> string
-- {path} --> stanza:find(path)
-- {{ns}name/child|each({ns}name){sub-template}}
--[[
template ::= "{" path ("|" name ("(" args ")")? (template)? )* "}"
path ::= defined by util.stanza
name ::= %w+
args ::= anything with balanced ( ) pairs
]]
local s_gsub = string.gsub;
local s_match = string.match;
local s_sub = string.sub;
local t_concat = table.concat;
local st = require "util.stanza";
local type escape_t = function (string) : string
local type filter_t = function (string, string | st.stanza_t, string) : string | st.stanza_t, boolean
local type filter_coll = { string : filter_t }
local function render(template : string, root : st.stanza_t, escape : escape_t, filters : filter_coll) : string
escape = escape or st.xml_escape;
return (s_gsub(template, "%b{}", function(block : string) : string
local inner = s_sub(block, 2, -2);
local path, pipe, pos = s_match(inner, "^([^|]+)(|?)()");
if not path is string then return end
local value : string | st.stanza_t
if path == "." then
value = root;
elseif path == "#" then
value = root:get_text();
else
value = root:find(path);
end
local is_escaped = false;
while pipe == "|" do
local func, args, tmpl, p = s_match(inner, "^(%w+)(%b())(%b{})()", pos as integer);
if not func then func, args, p = s_match(inner, "^(%w+)(%b())()", pos as integer); end
if not func then func, tmpl, p = s_match(inner, "^(%w+)(%b{})()", pos as integer); end
if not func then func, p = s_match(inner, "^(%w+)()", pos as integer); end
if not func then break end
if tmpl then tmpl = s_sub(tmpl, 2, -2); end
if args then args = s_sub(args, 2, -2); end
if func == "each" and tmpl and st.is_stanza(value) then
if not args then value, args = root, path; end
local ns, name = s_match(args, "^(%b{})(.*)$");
if ns then ns = s_sub(ns, 2, -2); else name, ns = args, nil; end
if ns == "" then ns = nil; end
if name == "" then name = nil; end
local out, i = {}, 1;
for c in (value as st.stanza_t):childtags(name, ns) do
out[i], i = render(tmpl, c, escape, filters), i + 1;
end
value = t_concat(out);
is_escaped = true;
elseif func == "and" and tmpl then
local condition = value;
if args then condition = root:find(args); end
if condition then
value = render(tmpl, root, escape, filters);
is_escaped = true;
end
elseif func == "or" and tmpl then
local condition = value;
if args then condition = root:find(args); end
if not condition then
value = render(tmpl, root, escape, filters);
is_escaped = true;
end
elseif filters and filters[func] then
local f = filters[func];
if args == nil then
value, is_escaped = f(value, tmpl);
else
value, is_escaped = f(args, value, tmpl);
end
else
error("No such filter function: " .. func);
end
pipe, pos = s_match(inner, "^(|?)()", p as integer);
end
if value is string then
if not is_escaped then value = escape(value); end
return value;
elseif st.is_stanza(value) then
value = value:get_text();
if value then
return escape(value);
end
end
return "";
end));
end
return { render = render };

86
util/xtemplate.lua Normal file
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local s_gsub = string.gsub;
local s_match = string.match;
local s_sub = string.sub;
local t_concat = table.concat;
local st = require("util.stanza");
local function render(template, root, escape, filters)
escape = escape or st.xml_escape;
return (s_gsub(template, "%b{}", function(block)
local inner = s_sub(block, 2, -2);
local path, pipe, pos = s_match(inner, "^([^|]+)(|?)()");
if not (type(path) == "string") then return end
local value
if path == "." then
value = root;
elseif path == "#" then
value = root:get_text();
else
value = root:find(path);
end
local is_escaped = false;
while pipe == "|" do
local func, args, tmpl, p = s_match(inner, "^(%w+)(%b())(%b{})()", pos);
if not func then func, args, p = s_match(inner, "^(%w+)(%b())()", pos); end
if not func then func, tmpl, p = s_match(inner, "^(%w+)(%b{})()", pos); end
if not func then func, p = s_match(inner, "^(%w+)()", pos); end
if not func then break end
if tmpl then tmpl = s_sub(tmpl, 2, -2); end
if args then args = s_sub(args, 2, -2); end
if func == "each" and tmpl and st.is_stanza(value) then
if not args then value, args = root, path; end
local ns, name = s_match(args, "^(%b{})(.*)$");
if ns then
ns = s_sub(ns, 2, -2);
else
name, ns = args, nil;
end
if ns == "" then ns = nil; end
if name == "" then name = nil; end
local out, i = {}, 1;
for c in (value):childtags(name, ns) do out[i], i = render(tmpl, c, escape, filters), i + 1; end
value = t_concat(out);
is_escaped = true;
elseif func == "and" and tmpl then
local condition = value;
if args then condition = root:find(args); end
if condition then
value = render(tmpl, root, escape, filters);
is_escaped = true;
end
elseif func == "or" and tmpl then
local condition = value;
if args then condition = root:find(args); end
if not condition then
value = render(tmpl, root, escape, filters);
is_escaped = true;
end
elseif filters and filters[func] then
local f = filters[func];
if args == nil then
value, is_escaped = f(value, tmpl);
else
value, is_escaped = f(args, value, tmpl);
end
else
error("No such filter function: " .. func);
end
pipe, pos = s_match(inner, "^(|?)()", p);
end
if type(value) == "string" then
if not is_escaped then value = escape(value); end
return value
elseif st.is_stanza(value) then
value = value:get_text();
if value then return escape(value) end
end
return ""
end))
end
return { render = render }