The function body search were too restrictive and ignored OOP-style functions and unicode named functions, resulting in a crash. This has been fixed. The error message for that specific error has been made for descriptive.

function.lua

@@ -55,6 +55,16 @@ end
 
 -- Constants
 
+-- FUNCTION_DEFINITION_MATCH is a lua pattern, for finding a function definition.
+-- NOTE: It will match malformed unicode sequences, and thus assumes that the
+-- string checked against have been checked by the lua interpreter.
+local FUNCTION_DEFINITION_MATCH =
+    '.*%f[%a_]function%f[^%a_]%s*'         .. -- Look for the function keyword
+	'([a-zA-Z0-9\128-\255_.:]*)'           .. -- Look for the function name, if any
+	'%s*(%([a-zA-Z0-9\128-\255_,. \t]*%))' .. -- Look for the function parameter list.
+	'[ \t]*(.+)[ \t]*'                     .. -- Look for the function body
+	'end'                                     -- Look for the end keyword
+
 local NR_CHARS_IN_LONG_FUNCTION_BODY = 30
 
 --------------------------------------------------------------------------------
@@ -139,10 +149,13 @@ local function get_function_paramlist_and_body (info)
     local end_line_index    =  get_line_index(str, info.lastlinedefined + 1)
 
 	-- Now find the function parameters and the function body.
-	local function_params, function_body  =  str:sub(start_line_index, end_line_index):match('.*%f[%a_]function%f[^%a_]%s*[a-zA-Z0-9_.]*%s*(%([a-zA-Z0-9_,. \t]*%))[ \t]*(.+)[ \t]*end')
+	local function_name, function_params, function_body  =  str:sub(start_line_index, end_line_index):match(FUNCTION_DEFINITION_MATCH)
-	assert(type(function_params) == 'string' and type(function_body) == 'string')
+	-- TODO: Use function_name for something.
+	if type(function_params) ~= 'string' or type(function_body) ~= 'string' then
+		error(('[pretty.function/internal]: Could not find the function defined on lines %i-%i (indices %i-%i) for string:\n\n%s\n'):format(info.linedefined, info.lastlinedefined, start_line_index, end_line_index, str))
+	end
 	function_body = function_body:match('^%s*(.-)%s*$')
-	assert(type(function_params) == 'string' and type(function_body) == 'string')
+	assert(type(function_body) == 'string')
 	-- And return them.
 	return function_params, function_body
 end

test/test_function.lua

@@ -34,7 +34,7 @@ local TEST_UPVALUE = 42
 -- Basic inline functions
 
 format_test {
-    name = 'Basic function formatting',
+    name = 'Function basic formatting',
     adv_getlocal = true,
     single = true,
     input  = function () end,
@@ -74,7 +74,7 @@ format_test {
 }
 
 format_test {
-    name = 'Closures don\'t affect functions printed in single mode 1',
+    name = 'Function with upvalues don\'t affected by them in single mode 1',
     adv_getlocal = true,
     single = true,
     input   = function () l = TEST_UPVALUE end,
@@ -82,7 +82,7 @@ format_test {
 }
 
 format_test {
-    name = 'Closures don\'t affect functions printed in single mode 2',
+    name = 'Function with upvalues don\'t affected by them in single mode 2',
     adv_getlocal = true,
     single = true,
     input  = function () TEST_UPVALUE = true end,
@@ -256,20 +256,21 @@ format_test {
 -- Embedding functions loaded with loadstring
 
 format_test {
+    name  = 'Embed functions loaded with loadstring',
     single = true,
-    name  = 'It\'s possible to get loadstring functions whole',
     input  = loadstring('return function (a, b) return a + b end')(),
     expect = 'function (a, b) return a + b end',
 }
 
 format_test {
+    name  = 'Embed functions with extra whitespace stripped',
     single = true,
-    name  = 'Whitespace is automatically stripped from loadstring functions',
     input  = loadstring('return function (a, b)\n    return a + b\nend')(),
     expect = 'function (a, b) return a + b end',
 }
 
 format_test {
+    name  = 'Embed nested function, when they end on different lines',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () return function () end\nend')()(),
@@ -277,7 +278,7 @@ format_test {
 }
 
 format_test {
-    name = 'When finding the correct function becomes too hard, just ignore it 1',
+    name = 'If embedding the correct function becomes too hard, ignore 1',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () return function () end end')(),
@@ -285,7 +286,7 @@ format_test {
 }
 
 format_test {
-    name = 'When finding the correct function becomes too hard, just ignore it 2',
+    name = 'If embedding the correct function becomes too hard, ignore 2',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () return function () end end')()(),
@@ -293,7 +294,7 @@ format_test {
 }
 
 format_test {
-    name   = 'Can still find body when body contains the word "function"',
+    name   = 'Embed functions which contains the word "function"',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () function_body() end')(),
@@ -301,7 +302,7 @@ format_test {
 }
 
 format_test {
-    name   = 'Can still find body when defined over objct',
+    name   = 'Embed functions defined with OOP style',
     single = true,
     adv_getlocal = true,
     input  = loadstring('local obj = {} \n function obj:a () return self end \n return obj.a')(),
@@ -309,7 +310,7 @@ format_test {
 }
 
 format_test {
-    name = 'Can find correct body, when body is on the same line, with different arguments',
+    name = 'Embed correct function, when two are on the same line, but with different arguments 1',
     single = true,
     adv_getlocal = true,
     input  = loadstring 'return { a = function (a) return a end, b = function (b) return b end }' ()['a'],
@@ -317,7 +318,15 @@ format_test {
 }
 
 format_test {
-    name   = 'Use dots when function body is somewhat long',
+    name = 'Embed correct function, when two are on the same line, but with different arguments 2',
+    single = true,
+    adv_getlocal = true,
+    input  = loadstring 'return { a = function (a) return a end, b = function (b) return b end }' ()['b'],
+    expect = 'function (b) return b end',
+}
+
+format_test {
+    name   = 'If embedding a function would be too long, ignore',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () return 1234578901235789012357890 end')(),
@@ -325,7 +334,7 @@ format_test {
 }
 
 format_test {
-    name   = 'Use dots when function body includes newline',
+    name   = 'If embedding a function would include newline, ignore',
     single = true,
     adv_getlocal = true,
     input  = loadstring('return function () -- Hi\n return 1234 end')(),
@@ -375,8 +384,8 @@ if HAS_UNICODE_IDEN then
     format_test {
         name = 'Align functions with unicode-named parameters nicely',
         adv_getlocal = true,
-        input  = loadstring 'return {\nψ = function (ψ) return ψ end,\nb = function (b) return b end\n}' (),
+        input  = loadstring 'return {\nfunction (ψ) return ψ end,\nfunction (b) return b end\n}' (),
-        expect = '{\n    ψ = function (ψ) return ψ end\n    b = function (b) return b end\n}',
+        expect = '{\n    function (ψ) return ψ end\n    function (b) return b end\n}',
     }
 end