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Salix (pronounced say-lix) is a Go templating engine inspired by Leaf.
Salix's syntax is similar to Leaf and (in my opinion at least), it's much more fun to write than the Go template syntax. If you like this project, please star the repo. I hope you enjoy! :)
Table of contents
Examples
Template
<html>
<head>
<title>#(page.Title)</title>
</head>
<body>
#for(i, user in users):
<div>
<h2>#(toLower(user.Name))</h2>
<p>User ID: #(i)</p>
#if(user.LoggedIn): <p>This user is logged in</p> #!if
#if(user.IsAdmin): <p>This user is an admin!</p> #!if
<p>Registered: #(user.RegisteredTime.Format("01-02-2006"))</p>
</div>
#!for
</body>
</html>
API Usage
t, err := salix.New().ParseFile("example.salix.txt")
if err != nil {
panic(err)
}
err = t.WithVarMap(vars).
WithTagMap(tags).
WithEscapeHTML(true).
Execute(os.Stdout)
if err != nil {
panic(err)
}
See the examples directory for more examples.
Tags
In Salix, tags have full control over the Abstract Syntax Tree (AST), which allows them to do things the language wouldn't ordinarily allow. Salix's if statements, for loops, macros, includes, etc. are implemented as tags.
Creating custom tags
You can extend the capabilities of Salix by creating custom tags. To create a custom tag, you need to implement the salix.Tag interface and add it to the tag map of your template or namespace using the WithTagMap method.
Salix tags follow a distinctive syntax pattern. They start with a pound sign (#), followed by a name and optional arguments. Tags can also enclose a block of content, and if they do, the block is terminated by an end tag with the same name. Here's an example of a template with both a macro tag and an include tag:
#macro("example"):
Content
#!macro
#include("template.html")
In this example:
- The
macrotag has a block, indicated by the content enclosed between#macro("example"):and#!macro. - The
includetag doesn't have a block; it simply includes the content oftemplate.html.
for tag
Salix's for tag is used for iterating over slices, arrays, and maps. It can assign one or two variables depending on your needs. When using a single variable, it sets that variable to the current element in the case of slices or arrays, or the current value for maps. With two variables, it assigns the first to the index (in the case of slices or arrays) or the key (for maps), and the second to the element or value, respectively. Here's an example of the for tag in action:
#for(id, name in users):
Name: #(name)
ID: #(id)
#!for
if tag
The if tag in Salix allows you to create conditional statements within your templates. It evaluates specified conditions and includes the enclosed content only if the condition is true. Here's an example:
#if(weather.Temp > 30):
<p>It's a hot day!</p>
#elif(weather.Temp < 0):
<p>It's freezing!</p>
#else:
<p>The temperature is between 0 and 30</p<
#!if
include tag
The include tag allows you to import content from other templates in the namespace, into your current template, making it easier to manage complex templates. Here's an example of the include tag:
#include("header.html")
Using the include tag with extra arguments
The include tag can accept extra local variables as arguments. Here's an example with a title variable:
#include("header.html", title = "Home")
These local variables will then be defined in the included template.
macro tag
The macro tag is a powerful feature that allows you to define reusable template sections. These sections can be included later in the current template or in other templates that were included by the include tag. Here's an example of the macro tag:
#macro("content"): <!-- This defines a macro called "content" -->
Content
#!macro
#macro("content") <!-- This inserts the content macro -->
When a macro tag has a block, it sets the macro's content. When it doesn't, it inserts the contents of the macro. In the above example, a macro is defined and then inserted.
Using the macro tag with extra arguments
Similar to the include tag, the macro tag can accept extra local variables as arguments. You can define these variables when including the macro. Here's an example:
#macro("content", x = 1, y = x + 2)
Functions
Functions used in a template can accept any number of arguments but are limited to returning a maximum of two values. When a function returns two values, the second one must be an error value.
Global Functions
Salix includes several useful global functions in all templates:
len(v any) int: Returns the length of the value passed in. If the length can't be found for the value passed in, it returns an error.toUpper(s string) string: Returnss, but with all characters mapped to their uppercase equivalents.toLower(s string) string: Returnss, but with all characters mapped to their lowercase equivalents.hasPrefix(s, prefix string) bool: Returns true ifsstarts withprefix.trimPrefix(s, prefix string) string: Returnss, but withprefixremoved from the beginning.hasSuffix(s, suffix string) bool: Returns true ifsends withsuffix.trimSuffix(s, suffix string) string: Returnss, but withsuffixremoved from the end.trimSpace(s string) string: Returnss, but with any whitespace characters removed from the beginning and end.equalFold(s1, s2 string) bool: Returns true ifs1is equal tos2under Unicode case-folding, which is a general form of case-insensitivity.count(s, substr string) int: Returns the amount of times thatsubstrappears ins.split(s, sep string) []string: Returns a slice containing all substrings separated bysep.join(ss []string, sep string) string: Returns a string with all substrings inssjoined bysep.
Adding Custom Functions
You can include custom functions as variables using the WithVarMap method on templates or namespaces. Methods that fit the above conditions can also be used as template functions.
Expressions
Salix's expressions mostly work like Go's, but there are some extra features worth mentioning.
Ternary Expressions
Salix supports ternary expressions, which allow you to choose a value based on whether a condition is true. For example:
#(len(matches) > 1 ? "several matches" : "one match")
This example returns "several matches" if the length of matches is greater than one. Otherwise, it returns "one match".
Coalescing operator
The coalescing operator allows you to return a default value if a variable isn't defined. Here's an example:
<title>#(title | "Home")</title>
In this case, the expression will return the content of the title variable if it's defined. If not, it will return "Home" as the default value.
The in operator
Salix's in operator allows you to check if a slice or array contains an element, if a map contains a key, or if a string contains a substring. Here's one example:
#("H" in "Hello") <!-- Returns true -->