Expand formatSimple() to support widths.

One of the highest-traffic users of String.format() is in the
notification code, which uses argument widths.  To support these
use-cases, this change adds argument width support, with tests.

Bug: 170978902
Test: atest error_prone_android_framework_test
Exempt-From-Owner-Approval: trivial additions
Change-Id: I8e36d4725a6d0cc896dedc5c457eb5f38486d7b6

4 files changed, 66 insertions, 7 deletions

diff --git a/core/java/android/text/TextUtils.java b/core/java/android/text/TextUtils.java
index 72b35b9253eb..d0fd2b393633 100644
--- a/core/java/android/text/TextUtils.java
+++ b/core/java/android/text/TextUtils.java
@@ -2095,6 +2095,9 @@ public class TextUtils {
      * <li>{@code %s} for {@code String}
      * <li>{@code %x} for hex representation of {@code int} or {@code long}
      * <li>{@code %%} for literal {@code %}
+     * <li>{@code %04d} style grammar to specify the argument width, such as
+     * {@code %04d} to prefix an {@code int} with zeros or {@code %10b} to
+     * prefix a {@code boolean} with spaces
      * </ul>
      *
      * @throws IllegalArgumentException if the format string or arguments don't
@@ -2106,8 +2109,23 @@ public class TextUtils {
         int j = 0;
         for (int i = 0; i < sb.length(); ) {
             if (sb.charAt(i) == '%') {
+                char code = sb.charAt(i + 1);
+
+                // Decode any argument width request
+                char prefixChar = '\0';
+                int prefixLen = 0;
+                int consume = 2;
+                while ('0' <= code && code <= '9') {
+                    if (prefixChar == '\0') {
+                        prefixChar = (code == '0') ? '0' : ' ';
+                    }
+                    prefixLen *= 10;
+                    prefixLen += Character.digit(code, 10);
+                    consume += 1;
+                    code = sb.charAt(i + consume - 1);
+                }
+
                 final String repl;
-                final char code = sb.charAt(i + 1);
                 switch (code) {
                     case 'b': {
                         if (j == args.length) {
@@ -2155,8 +2173,15 @@ public class TextUtils {
                         throw new IllegalArgumentException("Unsupported format code " + code);
                     }
                 }
-                sb.replace(i, i + 2, repl);
-                i += repl.length();
+
+                sb.replace(i, i + consume, repl);
+
+                // Apply any argument width request
+                final int prefixInsert = (prefixChar == '0' && repl.charAt(0) == '-') ? 1 : 0;
+                for (int k = repl.length(); k < prefixLen; k++) {
+                    sb.insert(i + prefixInsert, prefixChar);
+                }
+                i += Math.max(repl.length(), prefixLen);
             } else {
                 i++;
             }
diff --git a/core/tests/coretests/src/android/text/TextUtilsTest.java b/core/tests/coretests/src/android/text/TextUtilsTest.java
index 4e49118f438c..5362be337ede 100644
--- a/core/tests/coretests/src/android/text/TextUtilsTest.java
+++ b/core/tests/coretests/src/android/text/TextUtilsTest.java
@@ -822,6 +822,25 @@ public class TextUtilsTest {
     }
 
     @Test
+    public void testFormatSimple_Width() {
+        assertEquals("42", formatSimple("%1d", 42));
+        assertEquals("42", formatSimple("%2d", 42));
+        assertEquals(" 42", formatSimple("%3d", 42));
+        assertEquals("  42", formatSimple("%4d", 42));
+        assertEquals("  42  42", formatSimple("%4d%4d", 42, 42));
+        assertEquals(" -42", formatSimple("%4d", -42));
+        assertEquals("        42", formatSimple("%10d", 42));
+
+        assertEquals("42", formatSimple("%01d", 42));
+        assertEquals("42", formatSimple("%02d", 42));
+        assertEquals("042", formatSimple("%03d", 42));
+        assertEquals("0042", formatSimple("%04d", 42));
+        assertEquals("00420042", formatSimple("%04d%04d", 42, 42));
+        assertEquals("-042", formatSimple("%04d", -42));
+        assertEquals("0000000042", formatSimple("%010d", 42));
+    }
+
+    @Test
     public void testFormatSimple_Empty() {
         assertEquals("", formatSimple(""));
     }
@@ -833,6 +852,13 @@ public class TextUtilsTest {
     }
 
     @Test
+    public void testFormatSimple_Advanced() {
+        assertEquals("crtcl=0x002a:intrsv=Y:grnk=0x0018:gsmry=A:example:rnk=0x0000",
+                formatSimple("crtcl=0x%04x:intrsv=%c:grnk=0x%04x:gsmry=%c:%s:rnk=0x%04x",
+                        42, 'Y', 24, 'A', "example", 0));
+    }
+
+    @Test
     public void testFormatSimple_Mismatch() {
         try {
             formatSimple("%s");
diff --git a/errorprone/java/com/google/errorprone/bugpatterns/android/EfficientStringsChecker.java b/errorprone/java/com/google/errorprone/bugpatterns/android/EfficientStringsChecker.java
index d2cb030faef6..3a0fbd33933f 100644
--- a/errorprone/java/com/google/errorprone/bugpatterns/android/EfficientStringsChecker.java
+++ b/errorprone/java/com/google/errorprone/bugpatterns/android/EfficientStringsChecker.java
@@ -180,8 +180,10 @@ public final class EfficientStringsChecker extends BugChecker
         for (int i = 0; i < format.length(); i++) {
             char c = format.charAt(i);
             if (c == '%') {
-                i++;
-                c = format.charAt(i);
+                c = format.charAt(++i);
+                while ('0' <= c && c <= '9') {
+                    c = format.charAt(++i);
+                }
                 switch (c) {
                     case 'b':
                     case 'c':
diff --git a/errorprone/tests/java/com/google/errorprone/bugpatterns/android/EfficientStringsCheckerTest.java b/errorprone/tests/java/com/google/errorprone/bugpatterns/android/EfficientStringsCheckerTest.java
index ae9c316b8ca7..48e4ad11f9bf 100644
--- a/errorprone/tests/java/com/google/errorprone/bugpatterns/android/EfficientStringsCheckerTest.java
+++ b/errorprone/tests/java/com/google/errorprone/bugpatterns/android/EfficientStringsCheckerTest.java
@@ -41,9 +41,13 @@ public class EfficientStringsCheckerTest {
         assertTrue(EfficientStringsChecker.isSimple(""));
         assertTrue(EfficientStringsChecker.isSimple("%s"));
         assertTrue(EfficientStringsChecker.isSimple("String %s%s and %%%% number %d%d together"));
+        assertTrue(EfficientStringsChecker.isSimple("%04d"));
+        assertTrue(EfficientStringsChecker.isSimple("%02x:%02x:%02x"));
+        assertTrue(EfficientStringsChecker.isSimple("%10d"));
 
-        assertFalse(EfficientStringsChecker.isSimple("%04d"));
-        assertFalse(EfficientStringsChecker.isSimple("%02x:%02x:%02x"));
+        assertFalse(EfficientStringsChecker.isSimple("%0.4f"));
+        assertFalse(EfficientStringsChecker.isSimple("%t"));
+        assertFalse(EfficientStringsChecker.isSimple("%1$s"));
     }
 
     @Test
@@ -58,6 +62,7 @@ public class EfficientStringsCheckerTest {
                         "    String.format(\"foo %s bar\", str);",
                         "    // BUG: Diagnostic contains:",
                         "    String.format(\"foo %d bar\", 42);",
+                        "    // BUG: Diagnostic contains:",
                         "    String.format(\"foo %04d bar\", 42);",
                         "  }",
                         "  public void exampleLocale(String str) {",
@@ -66,6 +71,7 @@ public class EfficientStringsCheckerTest {
                         "    String.format(Locale.US, \"foo %s bar\", str);",
                         "    // BUG: Diagnostic contains:",
                         "    String.format(Locale.US, \"foo %d bar\", 42);",
+                        "    // BUG: Diagnostic contains:",
                         "    String.format(Locale.US, \"foo %04d bar\", 42);",
                         "  }",
                         "}")