String functions (trim, left, right, mid) - supports non string parameter

src/main/java/com/scriptbasic/utility/functions/StringFunctions.java

@@ -1,7 +1,9 @@
 package com.scriptbasic.utility.functions;
 
 import com.scriptbasic.api.BasicFunction;
+import com.scriptbasic.executors.rightvalues.BasicStringValue;
 import com.scriptbasic.interfaces.BasicRuntimeException;
+import com.scriptbasic.utility.RightValueUtility;
 
 /**
  * <p>
@@ -49,74 +51,116 @@ static public String chomp(final String s) {
         return s.replaceAll("\\n*$", "");
     }
 
+    /**
+     * Returns string for the argument.
+     * @param o argument to be converted
+     * @return string value
+     * @throws BasicRuntimeException failed to convert to string
+     */
+    @BasicFunction(classification = {com.scriptbasic.classification.String.class,
+            com.scriptbasic.classification.Utility.class})
+    static public String cstr(final Object o) throws BasicRuntimeException {
+        if (o == null) {
+            throw new BasicRuntimeException("Null cannot be converted to string");
+        }
+        if (o instanceof String) {
+            return (String) o;
+        }
+        return BasicStringValue.asString(RightValueUtility.createRightValue(o));
+    }
+
     /**
      * Trim the white spaces from the start of the string.
      *
-     * @param s the string to trim.
+     * @param o the string to trim.
      * @return the trimmed string
+     * @throws BasicRuntimeException if cannot convert to string
      */
     @BasicFunction(classification = {com.scriptbasic.classification.String.class,
             com.scriptbasic.classification.Utility.class})
-    static public String ltrim(final String s) {
+    static public String ltrim(final Object o) throws BasicRuntimeException {
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.replaceAll("^\\s*", "");
     }
 
     /**
      * Trim the white spaces from the end of the string.
      *
-     * @param s the string to trim
+     * @param o the string to trim
      * @return the trimmed string
+     * @throws BasicRuntimeException if cannot convert to string
      */
     @BasicFunction(classification = {com.scriptbasic.classification.String.class,
             com.scriptbasic.classification.Utility.class})
-    static public String rtrim(final String s) {
+    static public String rtrim(final Object o) throws BasicRuntimeException {
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.replaceAll("\\s*$", "");
     }
 
     /**
      * Return {@code len} number of characters from the left (the beginning) of the
      * string.
      *
-     * @param s   parameter
+     * @param o   parameter
      * @param len parameter
      * @return return value
+     * @throws BasicRuntimeException if cannot convert to string
      */
     @BasicFunction(classification = {com.scriptbasic.classification.String.class,
             com.scriptbasic.classification.Utility.class})
-    static public String left(final String s, final int len) {
+    static public String left(final Object o, final int len) throws BasicRuntimeException {
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.length() > len ? s.substring(0, len) : s;
     }
 
     /**
      * Return a substring from the string that starts at the position
      * {@code start} and has a length of {@code len}.
      *
-     * @param s     parameter
+     * @param o     parameter
      * @param start parameter
      * @param len   parameter
      * @return return value
      * @throws BasicRuntimeException incorrect parameter
      */
     @BasicFunction(classification = {com.scriptbasic.classification.String.class,
             com.scriptbasic.classification.Utility.class})
-    static public String mid(final String s, final int start, final int len) throws BasicRuntimeException {
+    static public String mid(final Object o, final int start, final int len) throws BasicRuntimeException {
         if (start < 1) {
             throw new BasicRuntimeException("Incorrect value in parameter start: " + start);
         }
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.substring(start - 1, start - 1 + len);
     }
 
     /**
      * Return {@code len} number of characters from the right (the end) of the
      * string.
      *
-     * @param s   parameter
+     * @param o   parameter
      * @param len parameter
      * @return return value
+     * @throws BasicRuntimeException if cannot convert to string
      */
     @BasicFunction(classification = {com.scriptbasic.classification.String.class,
             com.scriptbasic.classification.Utility.class})
-    static public String right(final String s, final int len) {
+    static public String right(final Object o, final int len) throws BasicRuntimeException {
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.length() > len ? s.substring(s.length() - len) : s;
     }
 
@@ -185,7 +229,11 @@ static public String lcase(final String s) {
     }
 
     @BasicFunction(classification = {com.scriptbasic.classification.String.class})
-    static public String trim(final String s) {
+    static public String trim(final Object o) throws BasicRuntimeException {
+        if (o == null) {
+            return null;
+        }
+        final String s = cstr(o);
         return s.trim();
     }
 

src/main/java/com/scriptbasic/utility/functions/UtilityFunctions.java

@@ -85,6 +85,15 @@ static public Boolean isDefined(final Object s) {
         return s != null;
     }
 
+    /**
+     * @param s is some value or object
+     * @return true if the parameter is null
+     */
+    @BasicFunction(classification = Utility.class)
+    static public Boolean isNull(final Object s) {
+        return s == null;
+    }
+
     /**
      * Create a new byte buffer of length {@code len}.
      *

src/test/resources/com/scriptbasic/testprograms/TestStringFunctions.bas

@@ -1,3 +1,24 @@
+' Test ltrim, trim, rtrim functions
+v = 1234
+assert("ltrim_with_num", ltrim(v)="1234")
+assert("trim_with_num", trim(v)="1234")
+assert("rtrim_with_num", rtrim(v)="1234")
+
+v = " 1234 "
+assert("ltrim", ltrim(v)="1234 ")
+assert("trim", trim(v)="1234")
+assert("rtrim", rtrim(v)=" 1234")
+
+' Test null values
+assert("ltrim_with_null", IsNull(ltrim(undefined_var)))
+assert("trim_with_null", IsNull(trim(undefined_var)))
+assert("rtrim_with_null", IsNull(rtrim(undefined_var)))
+
+' Test left, mid, right functions
+v = 1234
+assert("left_with_num", left(v,2)="12")
+assert("mid_with_num", mid(v,2,3)="234")
+assert("right_with_num", right(v,2)="34")
 v = "0123456789"
 PRINT left(v,2)
 PRINT RIGHT(v,2)