Re: [GSoC][PATCH] userdiff: add built-in pattern for golang

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Feb 28, 2018, 18:47 UTC
Message-ID: <CAPig+cTOv+jAQHA8p76MHcbbvv4SAs4y_1BxeRpexWwTT4+8hA@mail.gmail.com>
In-Reply-To: <20180228172906.30582-1-alban.gruin@gmail.com>

On Wed, Feb 28, 2018 at 12:29 PM, Alban Gruin <alban.gruin@gmail.com> wrote:

> This adds xfuncname and word_regex patterns for golang, a quite
> popular programming language. It also includes test cases for the
> xfuncname regex (t4018) and an updated documentation.

s/an //

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> The xfuncname regex finds functions, structs and interfaces. The
> word_regex pattern finds identifiers, integers, floats, complex
> numbers and operators, according to the go specification.
>
> Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
> ---
> diff --git a/t/t4018/golang-complex-function b/t/t4018/golang-complex-function
> @@ -0,0 +1,8 @@
> +func (t *Test) RIGHT(a Type) (Type, error) {
> +       t.a = a
> +        return ChangeMe, nil
> +}

Most of these files use a mix of spaces and tabs for indentation. Please use tabs only.

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> diff --git a/userdiff.c b/userdiff.c
> @@ -38,6 +38,15 @@ IPATTERN("fortran",
> +PATTERNS("golang",
> +        /* Functions */
> +        "^[ \t]*(func[ \t]*.*(\\{[ \t]*)?)\n"

Why is the brace (and possible following whitespace) optional? Considering that the language demands that the brace be on the same line, I'd think the brace should be mandatory.

I suppose you made whitespace after 'func' optional to be able to recognize a method (which hasn't been gofmt'd):

    func(x *X) name {

rather than the more typical:

    func (x *X) name {

I wonder if it would make sense to tighten the expression to recognize functions and methods as distinct cases:

    function: mandatory whitespace following 'func'
    method: optional whitespace but mandatory '(' following 'func'

Your current expression could accidentally match:

    /*
      Fish like to have
      functors for lunch {
      just like eels}.
    */

but, even the suggested tighter expression could "accidentally" match example code in a comment block anyhow, so I guess it probably doesn't matter much in practice.

> +        /* Structs and interfaces */
> +        "^[ \t]*(type[ \t].*(struct|interface)[ \t]*(\\{[ \t]*)?)",

Whitespace is required after 'type'. Good. The language doesn't require '{' to be on the same line as 'struct' or 'interface', and this expression makes it optional. Okay.

> +        /* -- */
> +        "[a-zA-Z_][a-zA-Z0-9_]*"
> +        "|[-+0-9.eE]+i?|0[xX]?[0-9a-fA-F]+i?"
> +        "|[-+*/<>%&^|=!:]=|--|\\+\\+|<<=?|>>=?|&\\^=?|&&|\\|\\||<-|\\.{3}"),