utilities.lua

--- Table Helpers
--- =============

--- # Printing Tables

function table.val_to_str ( v )
    if "string" == type( v ) then
        v = string.gsub( v, "\n", "\\n" )
        if string.match( string.gsub(v,"[^'\"]",""), '^"+$' ) then
            return "'" .. v .. "'"
        end
        return '"' .. string.gsub(v,'"', '\\"' ) .. '"'
    else
        return "table" == type( v ) and table.tostring( v ) or tostring( v )
    end
end

function table.key_to_str ( k )
    if "string" == type( k ) and string.match( k, "^[_%a][_%a%d]*$" ) then
        return k
    else
        return "[" .. table.val_to_str( k ) .. "]"
    end
end

function table.tostring( tbl )
    local result, done = {}, {}
    for k, v in ipairs( tbl ) do
        table.insert( result, table.val_to_str( v ) )
        done[ k ] = true
    end
    for k, v in pairs( tbl ) do
        if not done[ k ] then
            table.insert( result,
            table.key_to_str( k ) .. "=" .. table.val_to_str( v ) )
        end
    end
    return "{" .. table.concat( result, "," ) .. "}"
end

--- # Comparing Tables

function deepcompare(t1,t2,ignore_mt)
    local ty1 = type(t1)
    local ty2 = type(t2)
    if ty1 ~= ty2 then return false end
    -- non-table types can be directly compared
    if ty1 ~= 'table' and ty2 ~= 'table' then return t1 == t2 end
    -- as well as tables which have the metamethod __eq
    local mt = getmetatable(t1)
    if not ignore_mt and mt and mt.__eq then return t1 == t2 end
    for k1,v1 in pairs(t1) do
        local v2 = t2[k1]
        if v2 == nil or not deepcompare(v1,v2) then return false end
    end
    for k2,v2 in pairs(t2) do
        local v1 = t1[k2]
        if v1 == nil or not deepcompare(v1,v2) then return false end
    end
    return true
end

--- # Table element containment

function table.contains(tab, elem)
    for _,i in pairs(tab) do
        if deepcompare(i, elem) then
            return true
        end
    end
    return false
end

--- String Matching
--- ===============

function matches_token(input, token)
    return string.match(input, '^' .. token, 1)
end