r4d 0.3.1

R4d (Rad)

R4d is a text oriented macro prosessor made with rust.

NOTE

R4d is in very early stage, so there might be lots of undetected bugs. Fast implementaiton was my priorites, thus optimization has had a least consideration for the time.

Usage

# Usage : rad [OPTIONS] [FILE]...

# Read from file and save to file
rad input_file.txt -o out_file.txt

# Read from file and print to stdout 
rad input_file.txt

# Read from standard input and print to file
printf '...text...' | rad -o out_file.txt

# Read from stdin and print to stdout 
printf '...text...' | rad 

# Use following options to decide error behaviours
# default is stderr
rad -e FileToWriteError.txt # Log error to file
rad -s # Suppress error
rad -n # Always use unix newline (default is '\r\n' in windows platform)

# Freeze rule to a file
rad test -f frozen.r4f
# Melt a file and use in processing
rad test -m frozen.r4f

Type -h or --help to see full options.

Syntax

Macro definition

Definition syntax is similar to macro invocation but requires a specific form to sucessfully register the macro.

$define(name,arg1 arg2=$arg1() $arg2())

• First argument is a macro name. Macro should start with an alphabet character and following characters should be either alphanumeric or underscore.
• Second argument is macro's arguments. Macro argument also follows same rule of naming. Multiple arguments can be declared and should be separated by a whitespace.
• Third argument is a macro body. Any text can be included in the macro body while an unbalanced parenthesis will prevent processor's work. Enclose the body with literal syntax or escape with backslash to type literal parenthesis. Other than that any character including newlines('\n', "\r\n") are all respected (UTF-8). Even literal syntax itself is included.

You can simply bind the value without giving arguments.

$define(v_name=Simon creek)

Caveats

Definition's body can include any macro invocation in itself, thus wrong argument declaration cannot be detected at the time of definition.

$define(panik,kalm=$calm())
$panik()
===
error: Failed to invoke a macro : "calm"
 --> stdin:2:2
$calm()

Macro inovokation

Prefix is a dollar sign($)

$define(macro_name,a1 a2=$a1() $a2())
$macro_name(arg1, arg2)

Macro can be invoked anywhere after the definition.

My name is $macro_name(Simon, Creek).

converts to

My name is Simon Creek.

Special argument $: is used for iterated value.

$foreach(\*John,Simon,Jane*\,Name : $:
)
$forloop(5,10,$:th
)

converts to

Name : John
Name : Simon
Name : Jane

5th
6th
7th
8th
9th
10th

NOTE

An unbalanced parenthesis changes the behaviour of macro invocation and a non-double-quoted comma will change the number or content of arguments. If desirable content includes unbalanced parentheses or commas, enclose the body with string literal with the syntax of \* TEXT GOES HERE *\

$repeat(2,I'm,comma,separated
)
===
I'mI'm

To include commas you need to enclose with string literal

$repeat(2,\*I'm,comma,separated*\
)
===
I'm,comma,separated
I'm,comma,separated

Advanced features

Greedy macro

$define(test,a b c=$a() $b() $c())
$test(first, second, third, fourth, fifth, sixth)
$test+(first, second, third, fourth, fifth, sixth)
===
first  second  third
first  second  third, fourth, fifth, sixth

Piping

$define(test,a=$a())
$test|(I'm going to be used by a pipe macro)
$trim($repeat(2,$-()
))
$test|(\*I'll be requoted with literal*\)
$*()
===
I'm going to be used by a pipe macro
I'm going to be used by a pipe macro
\*I'll be requoted with literal*\

Goal

R4d aims to be a modern alternative to m4 processor, which means

• No trivial m4 quotes for macro definition
• Explicit rule for macro definition and usage so that de facto underscore rule is not necessary
• Easier binding with other programming languages(Rust's c binding)
• Enable combination of file stream and stdout
• As expressive as current m4 macro processor

Built-in macros (or macro-like functions)

Usages

Yet to come

• Compiled rule file a.k.a. m4 frozen file
• Combination of stdin and file input
• And possibly some optimizations...