More Robust Quoted Strings

[andrewstarks]

Hey Steve,

I wanted to share this work with you, in case you found it useful. Please ignore/reject it if you don't find that it fits with Penlight's goals.

This pull request includes stringx.quote_string and changes to pretty.write. quote_string wraps a string such that reloading that string from a chunk of Lua code produces identical results:

mystr = "\n[[\n My tricky ]======] string.\n]]"
mystr2 = load("return " .. stringx.quote_string(mystr))()
assert(mystr == mystr2)

It provides the same facilities as ("%q"):format(str), plus:

• Uses long quotes when it finds a pattern that matches the long-quote pattern (begin or end, balance doesn't matter) or when it finds a \n.
• Adds an extra \n at the beginning, if found.
• When Long quotes are used, it always uses a number of = signs that is one greater than any long-quotes that are embedded into the string.

The second, and highly related, changes were to pretty.write:

• Uses stringx.quote_string instead of internal, literal methods.
• Adds a space in front and in back of string, when long strings are used for key values:

my_table = {
    [ [[
My crazy key
]] ] = "foo"
}

• Because of the first change, now embedded long-strings can round-trip through the pretty printer. Nested long-strings would not compile in Lua.

Finally, a small patch was added for pretty.number:

• Added check for Lua 5.3. Locally patched tostring so that it returns 123 instead of 123.0. Without this patch, pretty.number was broken.

I also added tests and local function documentation, although this should be re-read and verified before accepting.

[stevedonovan]

Thanks, Andrew - I like robust at the moment!

[mpeterv]

Locally patched tostring so that it returns 123 instead of 123.0

It even returns 123 when formatting 123.456, neat.

[stevedonovan]

On Mon, Jul 18, 2016 at 12:24 PM, Peter Melnichenko <
notifications@github.com> wrote:

It even returns 123 when formatting 123.456, neat.

This is definitely more aggressive rounding than we need ;)