Templates may contain Lua statements and Lua expressions.
A statement is prefixed with |
, and extends to the end of the line:
|for i = 1, 10 do
| if i > 5 then
Hello, World!
| end
|end
Note that a statement may be preceded by whitespace only.
An expression is enclosed with ${}
, and may appear anywhere on a line:
${hello}, ${world}!
A template is parsed using templet.loadstring
:
local templet = require("templet")
local temp = templet.loadstring([[
|for i = 1, 10 do
| if i > 5 then
Hello, World!
| end
|end
]])
(Alternatively, a template is loaded from a file using templet.loadfile
.)
This creates a template object, which is then rendered:
local result = temp()
io.write(result)
Hello, World!
Hello, World!
Hello, World!
Hello, World!
Hello, World!
By default, a template is rendered in the global environment (_G
), i.e. variables in the template reference global variables. To substitute variables with values, the environment may be set by passing a table as the first argument:
local temp = templet.loadstring([[${hello}, ${world}!]])
print(temp({hello = "Hallo", world = "Welt"}))
print(temp({hello = "你好", world = "世界"}))
Hallo, Welt!
你好, 世界!
A template is rendered and returned as a string by default. Alternatively, an output function may be specified as the second argument, which is repeatedly called for the set of chunks that yield the rendered template.
local temp = templet.loadstring([[
|for i = 1, 3 do
double x${i} = ${math.sqrt(i)};
|end
]])
temp({math = math}, io.write)
double x1 = 1;
double x2 = 1.4142135623731;
double x3 = 1.7320508075689;
Suppose we wish to substitute floating-point values in a template using hexadecimal floating-point constants, which are an exact representation of binary values. We pass an output function that checks whether a chunk is a floating-point number, and converts to its hexadecimal representation:
temp({math = math}, function(chunk)
if type(chunk) == "number" and math.floor(chunk) ~= chunk then
chunk = string.format("%a", chunk)
end
return io.write(chunk)
end)
double x1 = 1;
double x2 = 0x1.6a09e667f3bcdp+0;
double x3 = 0x1.bb67ae8584caap+0;
Note that hexadecimal constants require Lua 5.2 or LuaJIT.