If constraints: check for same indent level

[wilzbach]

See also: dlang/dlang.org#1534

This is based on #348 as the sourceCode is needed to count the whitespace tokens at the beginning of the line.

[andralex]

I see you also made some refactorings here - nice.

[andralex]

cch @Hackerpilot :)

[wilzbach]

I see you also made some refactorings here - nice.

This is only #348 as this needs access to the raw sourceCode array to count the indentation level.

[wilzbach]

@Hackerpilot I am a bit stuck here.
As you stated on #348 you would prefer not to expose the raw source code to the plugins, which is
understandable. However, with only the token array at hand, how can I look ahead/back to the next/previous token (apart from iterating through the tokens array all the time)?
From what I learned the token doesn't know its position within the array, it only knows about:

type = the token type
text = the text of the token, which may be null
line = the line number at which this token occurs
column = the column number at which this token occurs
index = the byte offset from the beginning of the input at which this token occurs

Or to be more precise, for the indentation check the plugin looks at a couple of *Declarations in the AST. Then it compares the indent level of its constraint with the indent of the name token itself. For example for FunctionDeclaration:

override void visit(const FunctionDeclaration decl) {
	if (decl.constraint !is null)
		checkConstraintSpace(decl.constraint, decl.name);
}

Currently checkConstraintSpace is done by looking back until the beginning of the line and counting the seen whitespace characters, which is the indented level of the token:

auto lineIndent = code[0 .. constraint.location].retro
				.until('\n')
				.walkLength;

auto tokenLineStart = code[0 .. location].retro
						.until('\n')
						.walkLength;

auto tokenIndent = code[location - tokenLineStart .. location]
					.until!(x => !x.isWhite)
					.walkLength;

if (tokenIndent != lineIndent)
	addErrorMessage(constraint.expression.line, constraint.expression.column, KEY, MESSAGE);

How would I do this with merely the token array? Or can I (as proposed before) just pass the code array into the plugin (it's already in memory anyways).

[ghost]

@wilzbach

• you should also add a line to the readme.md, so far each check is briefly described.
• this PR actually fixes Warn about braces not on their own line #128, so you should add fix #128 - as prefix in the commit message.

[andralex]

@wilzbach @Hackerpilot I see this needs some rebasing, right?

[wilzbach]

@wilzbach @Hackerpilot I see this needs some rebasing, right?

Superseded by #450