knz/compose-text

Go text templating made easy

compose-text

Go text templating made easy

compose-text is a library that provides a text templating system easier to use than Go's standard template package.

It was inspired by the "StringTree" generator in capnp-scala.

How to use

1. go get github.com/knz/compose-text
2. import (. "github.com/knz/compose-text") in your source.
3. use S etc. in your code.

For example:

// Template for _ x _ = _ (newline)
var a, b, c int
t := L(&a, " x ", &b, " = ", &c)

// print the multiplication table of 7.
a = 7
for b = 1; b < 10; b++ {
  c = a * b
  t.Render(os.Stdout)
}

This produces the following output:

7 x 1 = 7
7 x 2 = 14
7 x 3 = 21
...
7 x 9 = 63

The following code can also be used instead of using pointers to variables:

// Template for _ x _ = _ (newline)
t := L(P("a"), " x ", P("b"), " = ", P("c"))

// print the multiplication table of 7.
for i := 1; i < 10; i++ {
  t.A("a", 7, "b", i, "c", i*7).Render(os.Stdout)
}

Another example:

// Template for a greeting.
g := L("hello, ", P("name"))

// Greet multiple people.
g.I("name", "jane", "mark", "isa").Render(os.Stdout)

Produces:

hello, jane
hello, mark
hello, isa

Supported template operators

S (sequence)

concatenation of zero or more templates.

L (line)

same as S followed by newline.

P (placeholder)

makes a "hole" template that can be filled by A or I.

A (apply)

applies a template to named arguments (creates a new template).

I (iterate)

"iterates" a template over a list of arguments (creates a new template equivalent to the concatenation of the results)

J (join)

joins the parts using a delimiter.

Methods on templates

Render(w io.Writer)

Executes the template to the specified writer.

RenderString() string

Executes the template and return the resulting text as string.

String() string

Produces a representation of the structure of the template (e.g. for troubleshooting)