From b42ff8338e30bd6101fee6ac507feb467aa4f935 Mon Sep 17 00:00:00 2001
From: Shekhar Gulati <shekhargulati84@gmail.com>
Date: Tue, 17 May 2016 20:10:15 +0530
Subject: [PATCH] Added support for `format` method. Still need to add support
 for named parameters.

---
 src/main/java/strman/Strman.java     | 24 ++++++++++++++++++++++++
 src/test/java/strman/StrmanTest.java | 15 +++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/main/java/strman/Strman.java b/src/main/java/strman/Strman.java
index a94485e..c689ef8 100644
--- a/src/main/java/strman/Strman.java
+++ b/src/main/java/strman/Strman.java
@@ -6,6 +6,8 @@ import java.util.Optional;
 import java.util.StringJoiner;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 import static java.util.stream.Collectors.joining;
@@ -416,6 +418,28 @@ public abstract class Strman {
         return first(value, 1);
     }
 
+    /**
+     * Formats a string using parameters
+     *
+     * @param value  The value to be formatted
+     * @param params Parameters to be described in the string
+     * @return The formatted string
+     */
+    public static String format(final String value, String... params) {
+        validate(value, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
+        Pattern p = Pattern.compile("\\{(\\w+)\\}");
+        Matcher m = p.matcher(value);
+        String result = value;
+        while (m.find()) {
+            int paramNumber = Integer.parseInt(m.group(1));
+            if (params == null || paramNumber >= params.length) {
+                throw new IllegalArgumentException("params does not have value for " + m.group());
+            }
+            result = result.replace(m.group(), params[paramNumber]);
+        }
+        return result;
+    }
+
     public static String leftPad(final String value, final String pad, final int length) {
         validate(value, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
         if (value.length() >= length) {
diff --git a/src/test/java/strman/StrmanTest.java b/src/test/java/strman/StrmanTest.java
index 62ebeb3..8eb2ed4 100644
--- a/src/test/java/strman/StrmanTest.java
+++ b/src/test/java/strman/StrmanTest.java
@@ -11,6 +11,7 @@ import static org.hamcrest.CoreMatchers.hasItems;
 import static org.hamcrest.collection.IsArrayContainingInOrder.arrayContaining;
 import static org.junit.Assert.*;
 import static strman.Strman.*;
+import static strman.Strman.format;
 
 public class StrmanTest {
 
@@ -327,4 +328,18 @@ public class StrmanTest {
 
         Arrays.stream(fixture).forEach(el -> assertThat(head(el), equalTo("f")));
     }
+
+    @Test
+    public void format_shouldFormatStringsToFooBar() throws Exception {
+        assertThat(format("{0} bar", "foo"), equalTo("foo bar"));
+        assertThat(format("foo {0}", "bar"), equalTo("foo bar"));
+        assertThat(format("foo {0}", "bar", "foo"), equalTo("foo bar"));
+        assertThat(format("{0} {1}", "foo", "bar"), equalTo("foo bar"));
+        assertThat(format("{1} {0}", "bar", "foo"), equalTo("foo bar"));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void format_shouldThrowExceptionWhenValueDoesNotExist() throws Exception {
+        assertThat(format("{1} {0}"), equalTo("{1} {0}"));
+    }
 }
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