1 files changed, 127 insertions, 0 deletions
diff --git a/src/backend/parser/scansup.c b/src/backend/parser/scansup.c
new file mode 100644
index 0000000..f55cacc
--- /dev/null
+++ b/src/backend/parser/scansup.c
@@ -0,0 +1,127 @@
+/*-------------------------------------------------------------------------
+ *
+ * scansup.c
+ *	  scanner support routines used by the core lexer
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/parser/scansup.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <ctype.h>
+
+#include "mb/pg_wchar.h"
+#include "parser/scansup.h"
+
+
+/*
+ * downcase_truncate_identifier() --- do appropriate downcasing and
+ * truncation of an unquoted identifier.  Optionally warn of truncation.
+ *
+ * Returns a palloc'd string containing the adjusted identifier.
+ *
+ * Note: in some usages the passed string is not null-terminated.
+ *
+ * Note: the API of this function is designed to allow for downcasing
+ * transformations that increase the string length, but we don't yet
+ * support that.  If you want to implement it, you'll need to fix
+ * SplitIdentifierString() in utils/adt/varlena.c.
+ */
+char *
+downcase_truncate_identifier(const char *ident, int len, bool warn)
+{
+	return downcase_identifier(ident, len, warn, true);
+}
+
+/*
+ * a workhorse for downcase_truncate_identifier
+ */
+char *
+downcase_identifier(const char *ident, int len, bool warn, bool truncate)
+{
+	char	   *result;
+	int			i;
+	bool		enc_is_single_byte;
+
+	result = palloc(len + 1);
+	enc_is_single_byte = pg_database_encoding_max_length() == 1;
+
+	/*
+	 * SQL99 specifies Unicode-aware case normalization, which we don't yet
+	 * have the infrastructure for.  Instead we use tolower() to provide a
+	 * locale-aware translation.  However, there are some locales where this
+	 * is not right either (eg, Turkish may do strange things with 'i' and
+	 * 'I').  Our current compromise is to use tolower() for characters with
+	 * the high bit set, as long as they aren't part of a multi-byte
+	 * character, and use an ASCII-only downcasing for 7-bit characters.
+	 */
+	for (i = 0; i < len; i++)
+	{
+		unsigned char ch = (unsigned char) ident[i];
+
+		if (ch >= 'A' && ch <= 'Z')
+			ch += 'a' - 'A';
+		else if (enc_is_single_byte && IS_HIGHBIT_SET(ch) && isupper(ch))
+			ch = tolower(ch);
+		result[i] = (char) ch;
+	}
+	result[i] = '\0';
+
+	if (i >= NAMEDATALEN && truncate)
+		truncate_identifier(result, i, warn);
+
+	return result;
+}
+
+
+/*
+ * truncate_identifier() --- truncate an identifier to NAMEDATALEN-1 bytes.
+ *
+ * The given string is modified in-place, if necessary.  A warning is
+ * issued if requested.
+ *
+ * We require the caller to pass in the string length since this saves a
+ * strlen() call in some common usages.
+ */
+void
+truncate_identifier(char *ident, int len, bool warn)
+{
+	if (len >= NAMEDATALEN)
+	{
+		len = pg_mbcliplen(ident, len, NAMEDATALEN - 1);
+		if (warn)
+			ereport(NOTICE,
+					(errcode(ERRCODE_NAME_TOO_LONG),
+					 errmsg("identifier \"%s\" will be truncated to \"%.*s\"",
+							ident, len, ident)));
+		ident[len] = '\0';
+	}
+}
+
+/*
+ * scanner_isspace() --- return true if flex scanner considers char whitespace
+ *
+ * This should be used instead of the potentially locale-dependent isspace()
+ * function when it's important to match the lexer's behavior.
+ *
+ * In principle we might need similar functions for isalnum etc, but for the
+ * moment only isspace seems needed.
+ */
+bool
+scanner_isspace(char ch)
+{
+	/* This must match scan.l's list of {space} characters */
+	if (ch == ' ' ||
+		ch == '\t' ||
+		ch == '\n' ||
+		ch == '\r' ||
+		ch == '\f')
+		return true;
+	return false;
+}