Extend CsvFile (#1702)

Provide ability to search headers without loading a row

modules/collect/src/main/java/com/opengamma/strata/collect/io/CsvFile.java

@@ -50,6 +50,10 @@ public final class CsvFile {
    * The header row, ordered as the headers appear in the file.
    */
   private final ImmutableList<String> headers;
+  /**
+   * The header map, transformed for case-insensitive searching.
+   */
+  private final ImmutableMap<String, Integer> searchHeaders;
   /**
    * The data rows in the CSV file.
    */
@@ -184,7 +188,7 @@ public static CsvFile of(List<String> headers, List<? extends List<String>> rows
     for (int i = 0; i < rows.size(); i++) {
       csvRows.add(new CsvRow(copiedHeaders, searchHeaders, i + firstLine, ImmutableList.copyOf(rows.get(i))));
     }
-    return new CsvFile(copiedHeaders, csvRows.build());
+    return new CsvFile(copiedHeaders, searchHeaders, csvRows.build());
   }
 
   //------------------------------------------------------------------------
@@ -203,7 +207,7 @@ private static CsvFile parseAll(
         rows.add(new CsvRow(headers, searchHeaders, i + 1, fields));
       }
     }
-    return new CsvFile(headers, rows.build());
+    return new CsvFile(headers, searchHeaders, rows.build());
   }
 
   // parse a single line
@@ -275,10 +279,12 @@ static ImmutableMap<String, Integer> buildSearchHeaders(ImmutableList<String> he
    * Restricted constructor.
    * 
    * @param headers  the header row
+   * @param searchHeaders  the headers transformed for searching
    * @param rows  the data rows
    */
-  private CsvFile(ImmutableList<String> headers, ImmutableList<CsvRow> rows) {
+  private CsvFile(ImmutableList<String> headers, ImmutableMap<String, Integer> searchHeaders, ImmutableList<CsvRow> rows) {
     this.headers = headers;
+    this.searchHeaders = searchHeaders;
     this.rows = rows;
   }
 
@@ -322,6 +328,17 @@ public CsvRow row(int index) {
     return rows.get(index);
   }
 
+  /**
+   * Checks if the file contains a header.
+   * <p>
+   * Matching is case insensitive.
+   * 
+   * @return the header row
+   */
+  public boolean containsHeader(String header) {
+    return searchHeaders.containsKey(header.toLowerCase(Locale.ENGLISH));
+  }
+
   //-------------------------------------------------------------------------
   /**
    * Checks if this CSV file equals another.

modules/collect/src/test/java/com/opengamma/strata/collect/io/CsvFileTest.java

@@ -90,6 +90,7 @@ public void test_of_empty_no_header() {
     CsvFile csvFile = CsvFile.of(CharSource.wrap(""), false);
     assertEquals(csvFile.headers().size(), 0);
     assertEquals(csvFile.rowCount(), 0);
+    assertEquals(csvFile.containsHeader("Foo"), false);
   }
 
   public void test_of_empty_with_header() {
@@ -100,6 +101,7 @@ public void test_of_simple_no_header() {
     CsvFile csvFile = CsvFile.of(CharSource.wrap(CSV1), false);
     assertEquals(csvFile.headers().size(), 0);
     assertEquals(csvFile.rowCount(), 4);
+    assertEquals(csvFile.containsHeader("Foo"), false);
     assertEquals(csvFile.row(0).lineNumber(), 1);
     assertEquals(csvFile.row(1).lineNumber(), 2);
     assertEquals(csvFile.row(2).lineNumber(), 3);
@@ -126,6 +128,7 @@ public void test_of_simple_no_header() {
   public void test_of_simple_no_header_tabs() {
     CsvFile csvFile = CsvFile.of(CharSource.wrap(CSV1T), false, '\t');
     assertEquals(csvFile.headers().size(), 0);
+    assertEquals(csvFile.containsHeader("Foo"), false);
     assertEquals(csvFile.rowCount(), 3);
     assertEquals(csvFile.row(0).lineNumber(), 1);
     assertEquals(csvFile.row(1).lineNumber(), 2);
@@ -147,6 +150,8 @@ public void test_of_simple_no_header_tabs() {
 
   public void test_of_simple_with_header() {
     CsvFile csvFile = CsvFile.of(CharSource.wrap(CSV1), true);
+    assertEquals(csvFile.containsHeader("Foo"), false);
+    assertEquals(csvFile.containsHeader("h1"), true);
     ImmutableList<String> headers = csvFile.headers();
     assertEquals(headers.size(), 2);
     assertEquals(headers.get(0), "h1");
@@ -221,6 +226,8 @@ public void test_of_simple_with_header() {
   public void test_of_duplicate_headers() {
     CsvFile csvFile = CsvFile.of(CharSource.wrap(CSV5), true);
     assertEquals(csvFile.headers(), ImmutableList.of("a", "b", "c", "b", "c"));
+    assertEquals(csvFile.containsHeader("Foo"), false);
+    assertEquals(csvFile.containsHeader("a"), true);
     assertEquals(csvFile.row(0).getField("a"), "aa");
     assertEquals(csvFile.row(0).getField("b"), "b1");
     assertEquals(csvFile.row(0).getField("c"), "c1");