Fix m2json case where val is empty

Author: robertoffmoura

plotly/plotly_aux/Test_m2json.m

@@ -3,132 +3,138 @@
         function testLowPrecisionInRange0to10(tc)
             values = 1 + (1:5) + 0.234;
             expected = "[2.234,3.234,4.234,5.234,6.234]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRange0to10(tc)
             values = 1 + (1:5) + 0.23456789;
             expected = "[2.23456789,3.23456789,4.23456789,5.23456789," ...
                     + "6.23456789]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function test2dArrayInRange0to10(tc)
             values = 1 + (1:5) + (0:1)' + 0.234;
             expected = "[[2.234,3.234,4.234,5.234,6.234]," ...
                     + "[3.234,4.234,5.234,6.234,7.234]]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testLowPrecisionInRange1e6to1e5(tc)
             values = 1e-6 * (1 + (1:5) + 0.234);
             expected = "[2.234e-06,3.234e-06,4.234e-06,5.234e-06," ...
                     + "6.234e-06]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRange1e6to1e5(tc)
             values = 1e-6 * (1 + (1:5) + 0.23456789);
             expected = "[2.23456789e-06,3.23456789e-06,4.23456789e-06," ...
                     + "5.23456789e-06,6.23456789e-06]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRange1e14Plus0to1(tc)
             values = 1e14 + (1:5) + 0.23456789;
             expected = "[100000000000001,100000000000002,"...
                     + "100000000000003,100000000000004,100000000000005]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRange1e14Plus1e7Plus0to1(tc)
             values = 1e14 + 1e7 + (1:5) + 0.23456789;
             expected = "[100000010000001,100000010000002," ...
                     + "100000010000003,100000010000004,100000010000005]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testLogScaledVariables(tc)
             values = 1e14 + 10.^(1:5) + 0.23456789;
             expected = "[100000000000010,100000000000100," ...
                     + "100000000001000,100000000010000,100000000100000]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testLowPrecisionInRangeMinus10to0(tc)
             values = -(1 + (1:5) + 0.234);
             expected = "[-2.234,-3.234,-4.234,-5.234,-6.234]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRangeMinus10to0(tc)
             values = -(1 + (1:5) + 0.23456789);
             expected = "[-2.23456789,-3.23456789,-4.23456789," ...
                     + "-5.23456789,-6.23456789]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRangeMinus1e5toMinus1e6(tc)
             values = -1e-6 * (1 + (1:5) + 0.23456789);
             expected = "[-2.23456789e-06,-3.23456789e-06," ...
                     + "-4.23456789e-06,-5.23456789e-06,-6.23456789e-06]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testInRangeMinus1e14Plus0to1(tc)
             values = -1e14 + (1:5) + 0.23456789;
             expected = "[-99999999999998.8,-99999999999997.8," ...
                     + "-99999999999996.8,-99999999999995.8," ...
                     + "-99999999999994.8]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
+        end
+
+        function testEmpty(tc)
+            values = [];
+            expected = "[]";
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testCell(tc)
             values = {1, "text", [1,2,3]};
             expected = "[1, ""text"", [1,2,3]]";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testStruct(tc)
             values = struct("a", 1, "b", "text");
             expected = "{""a"" : 1, ""b"" : ""text""}";
-            tc.verifyEqual(string(m2json(values)), expected);
+            tc.verifyEqual(m2json(values), expected);
         end
 
         function testDatetime(tc)
             value = datetime("2023-05-01 12:30:45");
             expected = """2023-05-01 12:30:45""";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
 
         function testDate(tc)
             value = datetime("2023-05-01");
             expected = """2023-05-01""";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
 
         function testLogicalTrue(tc)
             value = true;
             expected = "true";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
 
         function testLogicalFalse(tc)
             value = false;
             expected = "false";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
 
         function testCharArray(tc)
             value = 'Hello';
             expected = """Hello""";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
 
         function testString(tc)
             value = "World";
             expected = """World""";
-            tc.verifyEqual(string(m2json(value)), expected);
+            tc.verifyEqual(m2json(value), expected);
         end
     end
 end

plotly/plotly_aux/m2json.m

@@ -4,6 +4,10 @@
     elseif iscell(val)
         valstr = cell2json(val);
     elseif isa(val, "numeric")
+        if isempty(val)
+            valstr = "[]";
+            return;
+        end
         sz = size(val);
         if isa(val,"single")
             numDigits = 7;
@@ -25,8 +29,6 @@
         end
         if length(val)>1
             valstr = "[" + valstr + "]";
-        elseif isempty(val)
-            valstr = "[]";
         end
         valstr = strrep(valstr,"-Inf", "null");
         valstr = strrep(valstr, "Inf", "null");
@@ -38,7 +40,7 @@
              valstr = cell2json(cellstr(val));
          else
              val = checkescape(val); % add escape characters
-             valstr = sprintf('"%s"', val);
+             valstr = sprintf("""%s""", val);
          end
     elseif islogical(val)
         if val