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new 3ac702b CSV-278: Reuse Buffers in Lexer for Delimiter Detection (#162)
3ac702b is described below
commit 3ac702b190fd04c56118cb03aa87577f0a6a86f7
Author: belugabehr <12578579+belugab...@users.noreply.github.com>
AuthorDate: Thu Jul 15 09:41:22 2021 -0400
CSV-278: Reuse Buffers in Lexer for Delimiter Detection (#162)
* CSV-278: Reuse Buffers in Lexer for Delimiter Detection
* Remove erroneous tab character
* Reduce change set with fewer formatting changes
* Reduce change set with fewer formatting changes
---
.../apache/commons/csv/ExtendedBufferedReader.java | 15 +++++++++++++
src/main/java/org/apache/commons/csv/Lexer.java | 26 ++++++++++++----------
2 files changed, 29 insertions(+), 12 deletions(-)
diff --git a/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
b/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
index 63efb64..4b3fb48 100644
--- a/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
+++ b/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
@@ -132,6 +132,21 @@ final class ExtendedBufferedReader extends BufferedReader {
*/
char[] lookAhead(final int n) throws IOException {
final char[] buf = new char[n];
+ return lookAhead(buf);
+ }
+
+ /**
+ * Populates the buffer with the next {@code buf.length} characters in the
+ * current reader without consuming them. The next call to {@link #read()}
will
+ * still return the next value. This doesn't affect line number or last
+ * character.
+ *
+ * @param buf the buffer to fill for the look ahead.
+ * @return the buffer itself
+ * @throws IOException If an I/O error occurs
+ */
+ char[] lookAhead(final char[] buf) throws IOException {
+ final int n = buf.length;
super.mark(n);
super.read(buf, 0, n);
super.reset();
diff --git a/src/main/java/org/apache/commons/csv/Lexer.java
b/src/main/java/org/apache/commons/csv/Lexer.java
index cfd64fc..a8afc50 100644
--- a/src/main/java/org/apache/commons/csv/Lexer.java
+++ b/src/main/java/org/apache/commons/csv/Lexer.java
@@ -49,6 +49,8 @@ final class Lexer implements Closeable {
private static final char DISABLED = '\ufffe';
private final char[] delimiter;
+ private final char[] delimiterBuf;
+ private final char[] escapeDelimiterBuf;
private final char escape;
private final char quoteChar;
private final char commentStart;
@@ -68,6 +70,8 @@ final class Lexer implements Closeable {
this.commentStart = mapNullToDisabled(format.getCommentMarker());
this.ignoreSurroundingSpaces = format.getIgnoreSurroundingSpaces();
this.ignoreEmptyLines = format.getIgnoreEmptyLines();
+ this.delimiterBuf = new char[delimiter.length - 1];
+ this.escapeDelimiterBuf = new char[2 * delimiter.length - 1];
}
/**
@@ -112,7 +116,7 @@ final class Lexer implements Closeable {
}
/**
- * Determine whether the next characters constitute a delimiter through
{@link ExtendedBufferedReader#lookAhead(int)}
+ * Determine whether the next characters constitute a delimiter through
{@link ExtendedBufferedReader#lookAhead(char[])}.
*
* @param ch
* the current character.
@@ -126,14 +130,13 @@ final class Lexer implements Closeable {
if (delimiter.length == 1) {
return true;
}
- final int len = delimiter.length - 1;
- final char[] buf = reader.lookAhead(len);
- for (int i = 0; i < len; i++) {
- if (buf[i] != delimiter[i+1]) {
+ reader.lookAhead(delimiterBuf);
+ for (int i = 0; i < delimiterBuf.length; i++) {
+ if (delimiterBuf[i] != delimiter[i+1]) {
return false;
}
}
- final int count = reader.read(buf, 0, len);
+ final int count = reader.read(delimiterBuf, 0, delimiterBuf.length);
return count != END_OF_STREAM;
}
@@ -156,7 +159,7 @@ final class Lexer implements Closeable {
}
/**
- * Tests if the next characters constitute a escape delimiter through
{@link ExtendedBufferedReader#lookAhead(int)}.
+ * Tests if the next characters constitute a escape delimiter through
{@link ExtendedBufferedReader#lookAhead(char[])}.
*
* For example, for delimiter "[|]" and escape '!', return true if the
next characters constitute "![!|!]".
*
@@ -164,17 +167,16 @@ final class Lexer implements Closeable {
* @throws IOException If an I/O error occurs.
*/
boolean isEscapeDelimiter() throws IOException {
- final int len = 2 * delimiter.length - 1;
- final char[] buf = reader.lookAhead(len);
- if (buf[0] != delimiter[0]) {
+ reader.lookAhead(escapeDelimiterBuf);
+ if (escapeDelimiterBuf[0] != delimiter[0]) {
return false;
}
for (int i = 1; i < delimiter.length; i++) {
- if (buf[2 * i] != delimiter[i] || buf[2 * i - 1] != escape) {
+ if (escapeDelimiterBuf[2 * i] != delimiter[i] ||
escapeDelimiterBuf[2 * i - 1] != escape) {
return false;
}
}
- final int count = reader.read(buf, 0, len);
+ final int count = reader.read(escapeDelimiterBuf, 0,
escapeDelimiterBuf.length);
return count != END_OF_STREAM;
}
