Support the empty string as an enumeration value (#4450)

When a string enumeration has the empty string as one of its available
values, the generated code for many languages is invalid because the
empty string can not be used as an identifier.  As with numbers and
symbols, provide a mapping to an English name which can be used as a
replacement.  In this case, "empty" for the empty string/empty value.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>

modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java

@@ -303,6 +303,10 @@ public class DefaultCodegen {
      * @return the sanitized variable name for enum
      */
     public String toEnumVarName(String value, String datatype) {
+        if (value.length() == 0) {
+            return "EMPTY";
+        }
+
         String var = value.replaceAll("\\W+", "_").toUpperCase();
         if (var.matches("\\d.*")) {
             return "_" + var;

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractCSharpCodegen.java

@@ -615,6 +615,10 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "Empty";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(name) != null) {
             return camelize(getSymbolName(name));

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractJavaCodegen.java

@@ -808,6 +808,10 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
 
     @Override
     public String toEnumVarName(String value, String datatype) {
+        if (value.length() == 0) {
+            return "EMPTY";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(value) != null) {
             return getSymbolName(value).toUpperCase();

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractPhpCodegen.java

@@ -589,6 +589,10 @@ public abstract class AbstractPhpCodegen extends DefaultCodegen implements Codeg
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "EMPTY";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(name) != null) {
             return (getSymbolName(name)).toUpperCase();

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractTypeScriptClientCodegen.java

@@ -286,6 +286,10 @@ public abstract class AbstractTypeScriptClientCodegen extends DefaultCodegen imp
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "Empty";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(name) != null) {
             return camelize(getSymbolName(name));

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java

@@ -494,6 +494,10 @@ public class CSharpClientCodegen extends AbstractCSharpCodegen {
 
     @Override
     public String toEnumVarName(String value, String datatype) {
+        if (value.length() == 0) {
+            return "Empty";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(value) != null) {
             return camelize(getSymbolName(value));

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavascriptClientCodegen.java

@@ -1021,6 +1021,10 @@ public class JavascriptClientCodegen extends DefaultCodegen implements CodegenCo
 
     @Override
     public String toEnumVarName(String value, String datatype) {
+        if (value.length() == 0) {
+            return "empty";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(value) != null) {
             return (getSymbolName(value)).toUpperCase();

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/NancyFXServerCodegen.java

@@ -292,6 +292,10 @@ public class NancyFXServerCodegen extends AbstractCSharpCodegen {
 
     @Override
     public String toEnumVarName(final String name, final String datatype) {
+        if (name.length() == 0) {
+            return "Empty";
+        }
+
         final String enumName = camelize(
                 sanitizeName(name)
                 .replaceFirst("^_", "")

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java

@@ -644,6 +644,10 @@ public class PhpClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "EMPTY";
+        }
+
         // number
         if ("int".equals(datatype) || "double".equals(datatype) || "float".equals(datatype)) {
             String varName = name;

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/RubyClientCodegen.java

@@ -568,6 +568,10 @@ public class RubyClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "EMPTY";
+        }
+
         // number
         if ("Integer".equals(datatype) || "Float".equals(datatype)) {
             String varName = name;

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/Swift3Codegen.java

@@ -513,6 +513,10 @@ public class Swift3Codegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        if (name.length() == 0) {
+            return "empty";
+        }
+
         // for symbol, e.g. $, #
         if (getSymbolName(name) != null) {
             return camelize(WordUtils.capitalizeFully(getSymbolName(name).toUpperCase()), true);

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/SwiftCodegen.java

@@ -388,6 +388,10 @@ public class SwiftCodegen extends DefaultCodegen implements CodegenConfig {
 
     @SuppressWarnings("static-method")
     public String toSwiftyEnumName(String value) {
+        if (value.length() == 0) {
+            return "Empty";
+        }
+
         if (value.matches("^-?\\d*\\.{0,1}\\d+.*")) { // starts with number
             value = "Number" + value;
             value = value.replaceAll("-", "Minus");