Merge pull request #3900 from ZyX-I/inf-nan-string

Make it possible to eval() all floating-point values dumped by string()

7 files changed, 259 insertions, 11 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index acd9dc1865..3dbe98ab67 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -206,6 +206,12 @@ if(MSVC)
 else()
   add_definitions(-Wall -Wextra -pedantic -Wno-unused-parameter
     -Wstrict-prototypes -std=gnu99)
+
+  # On FreeBSD 64 math.h uses unguarded C11 extension, which taints clang
+  # 3.4.1 used there.
+  if(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+    add_definitions(-Wno-c11-extensions)
+  endif()
 endif()
 
 if(MINGW)
diff --git a/runtime/autoload/msgpack.vim b/runtime/autoload/msgpack.vim
index e6022922fe..2bb7ec5b02 100644
--- a/runtime/autoload/msgpack.vim
+++ b/runtime/autoload/msgpack.vim
@@ -395,7 +395,8 @@ endfunction
 ""
 " Dump floating-point value.
 function s:msgpack_dump_float(v) abort
-  return string(type(a:v) == type({}) ? a:v._VAL : a:v)
+  return substitute(string(type(a:v) == type({}) ? a:v._VAL : a:v),
+                   \'\V\^\(-\)\?str2float(''\(inf\|nan\)'')\$', '\1\2', '')
 endfunction
 
 ""
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 5dbef81748..ad736e9c81 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -6238,12 +6238,22 @@ string({expr})	Return {expr} converted to a String.  If {expr} is a Number,
 			{expr} type	result ~
 			String		'string'
 			Number		123
-			Float		123.123456 or 1.123456e8
-			Funcref		function('name')
+			Float		123.123456 or 1.123456e8 or 
+					`str2float('inf')`
+			Funcref		`function('name')`
 			List		[item, item]
 			Dictionary	{key: value, key: value}
 		Note that in String values the ' character is doubled.
 		Also see |strtrans()|.
+		Note 2: Output format is mostly compatible with YAML, except 
+		for infinite and NaN floating-point values representations 
+		which use |str2float()|.  Strings are also dumped literally, 
+		only single quote is escaped, which does not allow using YAML 
+		for parsing back binary strings (including text when 
+		'encoding' is not UTF-8).  |eval()| should always work for 
+		strings and floats though and this is the only official 
+		method, use |msgpackdump()| or |json_encode()| if you need to 
+		share data with other application.
 
 							*strlen()*
 strlen({expr})	The result is a Number, which is the length of the String
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index d3768409f5..8722fced26 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -99,6 +99,8 @@ are always available and may be used simultaneously in separate plugins.  The
    Same thing applies to |string()| (though it uses construct like 
    "{E724@level}"), but this is not reliable because |string()| continues to 
    error out.
+4. Stringifyed infinite and NaN values now use |str2float()| and can be evaled 
+   back.
 
 Viminfo text files were replaced with binary (messagepack) ShaDa files. 
 Additional differences:
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 982c14cd08..76deedfad0 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -4010,12 +4010,22 @@ eval6 (
        * When either side is a float the result is a float.
        */
       if (use_float) {
-        if (op == '*')
+        if (op == '*') {
           f1 = f1 * f2;
-        else if (op == '/') {
-          /* We rely on the floating point library to handle divide
-           * by zero to result in "inf" and not a crash. */
-          f1 = f2 != 0 ? f1 / f2 : INFINITY;
+        } else if (op == '/') {
+          // Division by zero triggers error from AddressSanitizer
+          f1 = (f2 == 0
+                ? (
+#ifdef NAN
+                    f1 == 0
+                    ? NAN
+                    :
+#endif
+                    (f1 > 0
+                     ? INFINITY
+                     : -INFINITY)
+                )
+                : f1 / f2);
         } else {
           EMSG(_("E804: Cannot use '%' with Float"));
           return FAIL;
@@ -6848,9 +6858,25 @@ vim_to_msgpack_error_ret: \
 
 #define CONV_FLOAT(flt) \
     do { \
-      char numbuf[NUMBUFLEN]; \
-      vim_snprintf(numbuf, NUMBUFLEN - 1, "%g", (flt)); \
-      ga_concat(gap, (char_u *) numbuf); \
+      const float_T flt_ = (flt); \
+      switch (fpclassify(flt_)) { \
+        case FP_NAN: { \
+          ga_concat(gap, (char_u *) "str2float('nan')"); \
+          break; \
+        } \
+        case FP_INFINITE: { \
+          if (flt_ < 0) { \
+            ga_append(gap, '-'); \
+          } \
+          ga_concat(gap, (char_u *) "str2float('inf')"); \
+          break; \
+        } \
+        default: { \
+          char numbuf[NUMBUFLEN]; \
+          vim_snprintf(numbuf, NUMBUFLEN - 1, "%g", flt_); \
+          ga_concat(gap, (char_u *) numbuf); \
+        } \
+      } \
     } while (0)
 
 #define CONV_FUNC(fun) \
diff --git a/test/functional/eval/operators_spec.lua b/test/functional/eval/operators_spec.lua
new file mode 100644
index 0000000000..bc9a17935c
--- /dev/null
+++ b/test/functional/eval/operators_spec.lua
@@ -0,0 +1,28 @@
+local helpers = require('test.functional.helpers')
+local eq = helpers.eq
+local eval = helpers.eval
+local clear = helpers.clear
+
+describe('Division operator', function()
+  before_each(clear)
+
+  it('returns infinity on {positive}/0.0', function()
+    eq('str2float(\'inf\')', eval('string(1.0/0.0)'))
+    eq('str2float(\'inf\')', eval('string(1.0e-100/0.0)'))
+    eq('str2float(\'inf\')', eval('string(1.0e+100/0.0)'))
+    eq('str2float(\'inf\')', eval('string((1.0/0.0)/0.0)'))
+  end)
+
+  it('returns -infinity on {negative}/0.0', function()
+    eq('-str2float(\'inf\')', eval('string((-1.0)/0.0)'))
+    eq('-str2float(\'inf\')', eval('string((-1.0e-100)/0.0)'))
+    eq('-str2float(\'inf\')', eval('string((-1.0e+100)/0.0)'))
+    eq('-str2float(\'inf\')', eval('string((-1.0/0.0)/0.0)'))
+  end)
+
+  it('returns NaN on 0.0/0.0', function()
+    eq('str2float(\'nan\')', eval('string(0.0/0.0)'))
+    eq('str2float(\'nan\')', eval('string(-(0.0/0.0))'))
+    eq('str2float(\'nan\')', eval('string((-0.0)/0.0)'))
+  end)
+end)
diff --git a/test/functional/eval/string_spec.lua b/test/functional/eval/string_spec.lua
new file mode 100644
index 0000000000..f7f5dca70a
--- /dev/null
+++ b/test/functional/eval/string_spec.lua
@@ -0,0 +1,175 @@
+local helpers = require('test.functional.helpers')
+local clear = helpers.clear
+local eq = helpers.eq
+local command = helpers.command
+local meths = helpers.meths
+local eval = helpers.eval
+local exc_exec = helpers.exc_exec
+local redir_exec = helpers.redir_exec
+local funcs = helpers.funcs
+local write_file = helpers.write_file
+
+describe('string() function', function()
+  before_each(clear)
+
+  describe('used to represent floating-point values', function()
+    it('dumps NaN values', function()
+      eq('str2float(\'nan\')', eval('string(str2float(\'nan\'))'))
+    end)
+
+    it('dumps infinite values', function()
+      eq('str2float(\'inf\')', eval('string(str2float(\'inf\'))'))
+      eq('-str2float(\'inf\')', eval('string(str2float(\'-inf\'))'))
+    end)
+
+    it('dumps regular values', function()
+      eq('1.5', funcs.string(1.5))
+      eq('1.56e-20', funcs.string(1.56000e-020))
+      eq('0.0', eval('string(0.0)'))
+    end)
+
+    it('dumps values with at most six digits after the decimal point',
+    function()
+      eq('1.234568e-20', funcs.string(1.23456789123456789123456789e-020))
+      eq('1.234568', funcs.string(1.23456789123456789123456789))
+    end)
+
+    it('dumps values with at most seven digits before the decimal point',
+    function()
+      eq('1234567.891235', funcs.string(1234567.89123456789123456789))
+      eq('1.234568e7', funcs.string(12345678.9123456789123456789))
+    end)
+
+    it('dumps negative values', function()
+      eq('-1.5', funcs.string(-1.5))
+      eq('-1.56e-20', funcs.string(-1.56000e-020))
+      eq('-1.234568e-20', funcs.string(-1.23456789123456789123456789e-020))
+      eq('-1.234568', funcs.string(-1.23456789123456789123456789))
+      eq('-1234567.891235', funcs.string(-1234567.89123456789123456789))
+      eq('-1.234568e7', funcs.string(-12345678.9123456789123456789))
+    end)
+  end)
+
+  describe('used to represent numbers', function()
+    it('dumps regular values', function()
+      eq('0', funcs.string(0))
+      eq('-1', funcs.string(-1))
+      eq('1', funcs.string(1))
+    end)
+
+    it('dumps large values', function()
+      eq('2147483647', funcs.string(2^31-1))
+      eq('-2147483648', funcs.string(-2^31))
+    end)
+  end)
+
+  describe('used to represent strings', function()
+    it('dumps regular strings', function()
+      eq('\'test\'', funcs.string('test'))
+    end)
+
+    it('dumps empty strings', function()
+      eq('\'\'', funcs.string(''))
+    end)
+
+    it('dumps strings with \' inside', function()
+      eq('\'\'\'\'\'\'\'\'', funcs.string('\'\'\''))
+      eq('\'a\'\'b\'\'\'\'\'', funcs.string('a\'b\'\''))
+      eq('\'\'\'b\'\'\'\'d\'', funcs.string('\'b\'\'d'))
+      eq('\'a\'\'b\'\'c\'\'d\'', funcs.string('a\'b\'c\'d'))
+    end)
+  end)
+
+  describe('used to represent funcrefs', function()
+    local fname = 'Xtest-functional-eval-string_spec-fref-script.vim'
+
+    before_each(function()
+      write_file(fname, [[
+        function Test1()
+        endfunction
+
+        function s:Test2()
+        endfunction
+
+        function g:Test3()
+        endfunction
+
+        let g:Test2_f = function('s:Test2')
+      ]])
+      command('source ' .. fname)
+    end)
+
+    after_each(function()
+      os.remove(fname)
+    end)
+
+    it('dumps references to built-in functions', function()
+      eq('function(\'function\')', eval('string(function("function"))'))
+    end)
+
+    it('dumps references to user functions', function()
+      eq('function(\'Test1\')', eval('string(function("Test1"))'))
+      eq('function(\'g:Test3\')', eval('string(function("g:Test3"))'))
+    end)
+
+    it('dumps references to script functions', function()
+      eq('function(\'<SNR>1_Test2\')', eval('string(Test2_f)'))
+    end)
+  end)
+
+  describe('used to represent lists', function()
+    it('dumps empty list', function()
+      eq('[]', funcs.string({}))
+    end)
+
+    it('dumps nested lists', function()
+      eq('[[[[[]]]]]', funcs.string({{{{{}}}}}))
+    end)
+
+    it('dumps nested non-empty lists', function()
+      eq('[1, [[3, [[5], 4]], 2]]', funcs.string({1, {{3, {{5}, 4}}, 2}}))
+    end)
+
+    it('errors when dumping recursive lists', function()
+      meths.set_var('l', {})
+      eval('add(l, l)')
+      eq('Vim(echo):E724: unable to correctly dump variable with self-referencing container',
+         exc_exec('echo string(l)'))
+    end)
+
+    it('dumps recursive lists despite the error', function()
+      meths.set_var('l', {})
+      eval('add(l, l)')
+      eq('\nE724: unable to correctly dump variable with self-referencing container\n[{E724@0}]',
+         redir_exec('echo string(l)'))
+      eq('\nE724: unable to correctly dump variable with self-referencing container\n[[{E724@1}]]',
+         redir_exec('echo string([l])'))
+    end)
+  end)
+
+  describe('used to represent dictionaries', function()
+    it('dumps empty dictionary', function()
+      eq('{}', eval('string({})'))
+    end)
+
+    it('dumps non-empty dictionary', function()
+      eq('{\'t\'\'est\': 1}', funcs.string({['t\'est']=1}))
+    end)
+
+    it('errors when dumping recursive dictionaries', function()
+      meths.set_var('d', {d=1})
+      eval('extend(d, {"d": d})')
+      eq('Vim(echo):E724: unable to correctly dump variable with self-referencing container',
+         exc_exec('echo string(d)'))
+    end)
+
+    it('dumps recursive dictionaries despite the error', function()
+      meths.set_var('d', {d=1})
+      eval('extend(d, {"d": d})')
+      eq('\nE724: unable to correctly dump variable with self-referencing container\n{\'d\': {E724@0}}',
+         redir_exec('echo string(d)'))
+      eq('\nE724: unable to correctly dump variable with self-referencing container\n{\'out\': {\'d\': {E724@1}}}',
+         redir_exec('echo string({"out": d})'))
+    end)
+  end)
+end)