Add ability to use symbols as field names instead of strings

Rakefile

@@ -69,7 +69,7 @@ $hoespec = Hoe.spec 'pg' do
 
 	self.spec_extras[:extensions] = [ 'ext/extconf.rb' ]
 
-	self.require_ruby_version( '>= 2.0.0' )
+	self.require_ruby_version( '>= 2.2' )
 
 	self.hg_sign_tags = true if self.respond_to?( :hg_sign_tags= )
 	self.check_history_on_release = true if self.respond_to?( :check_history_on_release= )

ext/pg.h

@@ -78,7 +78,7 @@ typedef long suseconds_t;
 #define RARRAY_AREF(a, i) (RARRAY_PTR(a)[i])
 #endif
 
-#define PG_ENC_IDX_BITS 30
+#define PG_ENC_IDX_BITS 28
 
 /* The data behind each PG::Connection object */
 typedef struct {
@@ -102,6 +102,8 @@ typedef struct {
 	VALUE decoder_for_get_copy_data;
 	/* Ruby encoding index of the client/internal encoding */
 	int enc_idx : PG_ENC_IDX_BITS;
+	/* flags controlling Symbol/String field names */
+	unsigned int flags : 2;
 
 #if defined(_WIN32)
 	/* File descriptor to be used for rb_w32_unwrap_io_handle() */
@@ -135,6 +137,9 @@ typedef struct {
 	 */
 	unsigned int autoclear : 1;
 
+	/* flags controlling Symbol/String field names */
+	unsigned int flags : 2;
+
 	/* Number of fields in fnames[] .
 	 * Set to -1 if fnames[] is not yet initialized.
 	 */
@@ -149,7 +154,7 @@ typedef struct {
 	/* Hash with fnames[] to field number mapping. */
 	VALUE field_map;
 
-	/* List of field names as frozen String objects.
+	/* List of field names as frozen String or Symbol objects.
 	 * Only valid if nfields != -1
 	 */
 	VALUE fnames[0];
@@ -165,6 +170,10 @@ typedef VALUE (* t_pg_typecast_result)(t_typemap *, VALUE, int, int);
 typedef t_pg_coder *(* t_pg_typecast_query_param)(t_typemap *, VALUE, int);
 typedef VALUE (* t_pg_typecast_copy_get)( t_typemap *, VALUE, int, int, int );
 
+#define PG_RESULT_FIELD_NAMES_MASK 0x03
+#define PG_RESULT_FIELD_NAMES_SYMBOL 0x01
+#define PG_RESULT_FIELD_NAMES_STATIC_SYMBOL 0x02
+
 #define PG_CODER_TIMESTAMP_DB_UTC 0x0
 #define PG_CODER_TIMESTAMP_DB_LOCAL 0x1
 #define PG_CODER_TIMESTAMP_APP_UTC 0x0

ext/pg_connection.c

@@ -13,6 +13,7 @@
 VALUE rb_cPGconn;
 static ID s_id_encode;
 static VALUE sym_type, sym_format, sym_value;
+static VALUE sym_symbol, sym_string, sym_static_symbol;
 
 static PQnoticeReceiver default_notice_receiver = NULL;
 static PQnoticeProcessor default_notice_processor = NULL;
@@ -4060,6 +4061,58 @@ pgconn_decoder_for_get_copy_data_get(VALUE self)
 	return this->decoder_for_get_copy_data;
 }
 
+/*
+ * call-seq:
+ *    conn.field_name_type = Symbol
+ *
+ * Set default type of field names of results retrieved by this connection.
+ * It can be set to one of:
+ * * +:string+ to use String based field names
+ * * +:symbol+ to use Symbol based field names
+ *
+ * The default is +:string+ .
+ *
+ * Settings the type of field names affects only future results.
+ *
+ * See further description at PG::Result#field_name_type=
+ *
+ */
+static VALUE
+pgconn_field_name_type_set(VALUE self, VALUE sym)
+{
+	t_pg_connection *this = pg_get_connection( self );
+
+	this->flags &= ~PG_RESULT_FIELD_NAMES_MASK;
+	if( sym == sym_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_SYMBOL;
+	else if ( sym == sym_static_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_STATIC_SYMBOL;
+	else if ( sym == sym_string );
+	else rb_raise(rb_eArgError, "invalid argument %+"PRIsVALUE, sym);
+
+	return sym;
+}
+
+/*
+ * call-seq:
+ *    conn.field_name_type -> Symbol
+ *
+ * Get type of field names.
+ *
+ * See description at #field_name_type=
+ */
+static VALUE
+pgconn_field_name_type_get(VALUE self)
+{
+	t_pg_connection *this = pg_get_connection( self );
+
+	if( this->flags & PG_RESULT_FIELD_NAMES_SYMBOL ){
+		return sym_symbol;
+	} else if( this->flags & PG_RESULT_FIELD_NAMES_STATIC_SYMBOL ){
+		return sym_static_symbol;
+	} else {
+		return sym_string;
+	}
+}
+
 
 /*
  * Document-class: PG::Connection
@@ -4071,6 +4124,9 @@ init_pg_connection()
 	sym_type = ID2SYM(rb_intern("type"));
 	sym_format = ID2SYM(rb_intern("format"));
 	sym_value = ID2SYM(rb_intern("value"));
+	sym_string = ID2SYM(rb_intern("string"));
+	sym_symbol = ID2SYM(rb_intern("symbol"));
+	sym_static_symbol = ID2SYM(rb_intern("static_symbol"));
 
 	rb_cPGconn = rb_define_class_under( rb_mPG, "Connection", rb_cObject );
 	rb_include_module(rb_cPGconn, rb_mPGconstants);
@@ -4255,4 +4311,7 @@ init_pg_connection()
 	rb_define_method(rb_cPGconn, "encoder_for_put_copy_data", pgconn_encoder_for_put_copy_data_get, 0);
 	rb_define_method(rb_cPGconn, "decoder_for_get_copy_data=", pgconn_decoder_for_get_copy_data_set, 1);
 	rb_define_method(rb_cPGconn, "decoder_for_get_copy_data", pgconn_decoder_for_get_copy_data_get, 0);
+
+	rb_define_method(rb_cPGconn, "field_name_type=", pgconn_field_name_type_set, 1 );
+	rb_define_method(rb_cPGconn, "field_name_type", pgconn_field_name_type_get, 0 );
 }

ext/pg_result.c

@@ -6,8 +6,8 @@
 
 #include "pg.h"
 
-
 VALUE rb_cPGresult;
+static VALUE sym_symbol, sym_string, sym_static_symbol;
 
 static VALUE pgresult_type_map_set( VALUE, VALUE );
 static t_pg_result *pgresult_get_this( VALUE );
@@ -190,6 +190,7 @@ pg_new_result2(PGresult *result, VALUE rb_pgconn)
 	this->nfields = -1;
 	this->tuple_hash = Qnil;
 	this->field_map = Qnil;
+	this->flags = 0;
 	self = TypedData_Wrap_Struct(rb_cPGresult, &pgresult_type, this);
 
 	if( result ){
@@ -201,6 +202,7 @@ pg_new_result2(PGresult *result, VALUE rb_pgconn)
 		this->enc_idx = p_conn->enc_idx;
 		this->typemap = p_typemap->funcs.fit_to_result( typemap, self );
 		this->p_typemap = DATA_PTR( this->typemap );
+		this->flags = p_conn->flags;
 	} else {
 		this->enc_idx = rb_locale_encindex();
 	}
@@ -404,6 +406,29 @@ pgresult_get(VALUE self)
 	return this->pgresult;
 }
 
+static VALUE pg_cstr_to_sym(char *cstr, unsigned int flags, int enc_idx)
+{
+	VALUE fname;
+	if( flags & PG_RESULT_FIELD_NAMES_SYMBOL ){
+#ifndef TRUFFLERUBY
+		rb_encoding *enc = rb_enc_from_index(enc_idx);
+		fname = rb_check_symbol_cstr(cstr, strlen(cstr), enc);
+		if( fname == Qnil ){
+			fname = rb_tainted_str_new2(cstr);
+			PG_ENCODING_SET_NOCHECK(fname, enc_idx);
+			fname = rb_str_intern(fname);
+		}
+	} else if( flags & PG_RESULT_FIELD_NAMES_STATIC_SYMBOL ){
+#endif
+		rb_encoding *enc = rb_enc_from_index(enc_idx);
+		fname = ID2SYM(rb_intern3(cstr, strlen(cstr), enc));
+	} else {
+		fname = rb_tainted_str_new2(cstr);
+		PG_ENCODING_SET_NOCHECK(fname, enc_idx);
+		fname = rb_obj_freeze(fname);
+	}
+	return fname;
+}
 
 static void pgresult_init_fnames(VALUE self)
 {
@@ -414,12 +439,9 @@ static void pgresult_init_fnames(VALUE self)
 		int nfields = PQnfields(this->pgresult);
 
 		for( i=0; i<nfields; i++ ){
-			VALUE fname = rb_tainted_str_new2(PQfname(this->pgresult, i));
-			PG_ENCODING_SET_NOCHECK(fname, this->enc_idx);
-			this->fnames[i] = rb_obj_freeze(fname);
+			char *cfname = PQfname(this->pgresult, i);
+			this->fnames[i] = pg_cstr_to_sym(cfname, this->flags, this->enc_idx);
 			this->nfields = i + 1;
-
-			RB_GC_GUARD(fname);
 		}
 		this->nfields = nfields;
 	}
@@ -597,24 +619,25 @@ pgresult_nfields(VALUE self)
 
 /*
  * call-seq:
- *    res.fname( index ) -> String
+ *    res.fname( index ) -> String or Symbol
  *
  * Returns the name of the column corresponding to _index_.
+ * Depending on #field_name_type= it's a String or Symbol.
+ *
  */
 static VALUE
 pgresult_fname(VALUE self, VALUE index)
 {
-	VALUE fname;
 	t_pg_result *this = pgresult_get_this_safe(self);
 	int i = NUM2INT(index);
+	char *cfname;
 
 	if (i < 0 || i >= PQnfields(this->pgresult)) {
 		rb_raise(rb_eArgError,"invalid field number %d", i);
 	}
 
-	fname = rb_tainted_str_new2(PQfname(this->pgresult, i));
-	PG_ENCODING_SET_NOCHECK(fname, this->enc_idx);
-	return rb_obj_freeze(fname);
+	cfname = PQfname(this->pgresult, i);
+	return pg_cstr_to_sym(cfname, this->flags, this->enc_idx);
 }
 
 /*
@@ -1115,8 +1138,12 @@ static VALUE
 pgresult_field_values( VALUE self, VALUE field )
 {
 	PGresult *result = pgresult_get( self );
-	const char *fieldname = StringValueCStr( field );
-	int fnum = PQfnumber( result, fieldname );
+	const char *fieldname;
+	int fnum;
+
+	if( RB_TYPE_P(field, T_SYMBOL) ) field = rb_sym_to_s( field );
+	fieldname = StringValueCStr( field );
+	fnum = PQfnumber( result, fieldname );
 
 	if ( fnum < 0 )
 		rb_raise( rb_eIndexError, "no such field '%s' in result", fieldname );
@@ -1230,7 +1257,7 @@ pgresult_each(VALUE self)
  * call-seq:
  *    res.fields() -> Array
  *
- * Returns an array of Strings representing the names of the fields in the result.
+ * Depending on #field_name_type= returns an array of strings or symbols representing the names of the fields in the result.
  */
 static VALUE
 pgresult_fields(VALUE self)
@@ -1466,10 +1493,70 @@ pgresult_stream_each_tuple(VALUE self)
 	return pgresult_stream_any(self, yield_tuple);
 }
 
+/*
+ * call-seq:
+ *    res.field_name_type = Symbol
+ *
+ * Set type of field names specific to this result.
+ * It can be set to one of:
+ * * +:string+ to use String based field names
+ * * +:symbol+ to use Symbol based field names
+ * * +:static_symbol+ to use pinned Symbol (can not be garbage collected) - Don't use this, it will probably removed in future.
+ *
+ * The default is retrieved from PG::Connection#field_name_type , which defaults to +:string+ .
+ *
+ * This setting affects several result methods:
+ * * keys of Hash returned by #[] , #each and #stream_each
+ * * #fields
+ * * #fname
+ * * field names used by #tuple and #stream_each_tuple
+ *
+ * The type of field names can only be changed before any of the affected methods have been called.
+ *
+ */
+static VALUE
+pgresult_field_name_type_set(VALUE self, VALUE sym)
+{
+	t_pg_result *this = pgresult_get_this(self);
+	if( this->nfields != -1 ) rb_raise(rb_eArgError, "field names are already materialized");
+
+	this->flags &= ~PG_RESULT_FIELD_NAMES_MASK;
+	if( sym == sym_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_SYMBOL;
+	else if ( sym == sym_static_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_STATIC_SYMBOL;
+	else if ( sym == sym_string );
+	else rb_raise(rb_eArgError, "invalid argument %+"PRIsVALUE, sym);
+
+	return sym;
+}
+
+/*
+ * call-seq:
+ *    res.field_name_type -> Symbol
+ *
+ * Get type of field names.
+ *
+ * See description at #field_name_type=
+ */
+static VALUE
+pgresult_field_name_type_get(VALUE self)
+{
+	t_pg_result *this = pgresult_get_this(self);
+	if( this->flags & PG_RESULT_FIELD_NAMES_SYMBOL ){
+		return sym_symbol;
+	} else if( this->flags & PG_RESULT_FIELD_NAMES_STATIC_SYMBOL ){
+		return sym_static_symbol;
+	} else {
+		return sym_string;
+	}
+}
 
 void
 init_pg_result()
 {
+	sym_string = ID2SYM(rb_intern("string"));
+	sym_symbol = ID2SYM(rb_intern("symbol"));
+	sym_static_symbol = ID2SYM(rb_intern("static_symbol"));
+
 	rb_cPGresult = rb_define_class_under( rb_mPG, "Result", rb_cData );
 	rb_include_module(rb_cPGresult, rb_mEnumerable);
 	rb_include_module(rb_cPGresult, rb_mPGconstants);
@@ -1526,4 +1613,7 @@ init_pg_result()
 	rb_define_method(rb_cPGresult, "stream_each", pgresult_stream_each, 0);
 	rb_define_method(rb_cPGresult, "stream_each_row", pgresult_stream_each_row, 0);
 	rb_define_method(rb_cPGresult, "stream_each_tuple", pgresult_stream_each_tuple, 0);
+
+	rb_define_method(rb_cPGresult, "field_name_type=", pgresult_field_name_type_set, 1 );
+	rb_define_method(rb_cPGresult, "field_name_type", pgresult_field_name_type_get, 0 );
 }

ext/pg_tuple.c

@@ -212,7 +212,7 @@ pg_tuple_materialize(t_pg_tuple *this)
  * An integer +key+ is interpreted as column index.
  * Negative values of index count from the end of the array.
  *
- * A string +key+ is interpreted as column name.
+ * Depending on Result#field_name_type= a string or symbol +key+ is interpreted as column name.
  *
  * If the key can't be found, there are several options:
  * With no other arguments, it will raise a IndexError exception;
@@ -265,9 +265,16 @@ pg_tuple_fetch(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
- *    res[ name ] -> value
+ *    tup[ key ] -> value
  *
- * Returns field _name_.
+ * Returns a field value by either column index or column name.
+ *
+ * An integer +key+ is interpreted as column index.
+ * Negative values of index count from the end of the array.
+ *
+ * Depending on Result#field_name_type= a string or symbol +key+ is interpreted as column name.
+ *
+ * If the key can't be found, it returns +nil+ .
  */
 static VALUE
 pg_tuple_aref(VALUE self, VALUE key)

lib/pg/result.rb

@@ -9,12 +9,23 @@ class PG::Result
 	#
 	# +type_map+: a PG::TypeMap instance.
 	#
-	# See PG::BasicTypeMapForResults
+	# This method is equal to #type_map= , but returns self, so that calls can be chained.
+	#
+	# See also PG::BasicTypeMapForResults
 	def map_types!(type_map)
 		self.type_map = type_map
 		return self
 	end
 
+	# Set the data type for all field name returning methods.
+	#
+	# +type+: a Symbol defining the field name type.
+	#
+	# This method is equal to #field_name_type= , but returns self, so that calls can be chained.
+	def field_names_as(type)
+		self.field_name_type = type
+		return self
+	end
 
 	### Return a String representation of the object suitable for debugging.
 	def inspect