sql/*: implement show collation

Signed-off-by: Miguel Molina <[email protected]>

Author: erizocosmico

engine_test.go

@@ -800,6 +800,26 @@ var queries = []struct {
 			{nil},
 		},
 	},
+	{
+		`SHOW COLLATION`,
+		[]sql.Row{{"utf8_bin", "utf8mb4", int64(1), "Yes", "Yes", int64(1)}},
+	},
+	{
+		`SHOW COLLATION LIKE 'foo'`,
+		[]sql.Row{},
+	},
+	{
+		`SHOW COLLATION LIKE 'utf8%'`,
+		[]sql.Row{{"utf8_bin", "utf8mb4", int64(1), "Yes", "Yes", int64(1)}},
+	},
+	{
+		`SHOW COLLATION WHERE charset = 'foo'`,
+		[]sql.Row{},
+	},
+	{
+		"SHOW COLLATION WHERE `Default` = 'Yes'",
+		[]sql.Row{{"utf8_bin", "utf8mb4", int64(1), "Yes", "Yes", int64(1)}},
+	},
 }
 
 func TestQueries(t *testing.T) {

sql/parse/parse.go

@@ -43,6 +43,7 @@ var (
 	showCreateRegex      = regexp.MustCompile(`^show create\s+\S+\s*`)
 	showVariablesRegex   = regexp.MustCompile(`^show\s+(.*)?variables\s*`)
 	showWarningsRegex    = regexp.MustCompile(`^show\s+warnings\s*`)
+	showCollationRegex   = regexp.MustCompile(`^show\s+collation\s*`)
 	describeRegex        = regexp.MustCompile(`^(describe|desc|explain)\s+(.*)\s+`)
 	fullProcessListRegex = regexp.MustCompile(`^show\s+(full\s+)?processlist$`)
 	unlockTablesRegex    = regexp.MustCompile(`^unlock\s+tables$`)
@@ -82,6 +83,8 @@ func Parse(ctx *sql.Context, query string) (sql.Node, error) {
 		return parseShowVariables(ctx, s)
 	case showWarningsRegex.MatchString(lowerQuery):
 		return parseShowWarnings(ctx, s)
+	case showCollationRegex.MatchString(lowerQuery):
+		return parseShowCollation(s)
 	case describeRegex.MatchString(lowerQuery):
 		return parseDescribeQuery(ctx, s)
 	case fullProcessListRegex.MatchString(lowerQuery):
@@ -1190,6 +1193,63 @@ func parseShowTableStatus(query string) (sql.Node, error) {
 	}
 }
 
+func parseShowCollation(query string) (sql.Node, error) {
+	buf := bufio.NewReader(strings.NewReader(query))
+	err := parseFuncs{
+		expect("show"),
+		skipSpaces,
+		expect("collation"),
+		skipSpaces,
+	}.exec(buf)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if _, err = buf.Peek(1); err == io.EOF {
+		return plan.NewShowCollation(), nil
+	}
+
+	var clause string
+	if err := readIdent(&clause)(buf); err != nil {
+		return nil, err
+	}
+
+	if err := skipSpaces(buf); err != nil {
+		return nil, err
+	}
+
+	switch strings.ToUpper(clause) {
+	case "WHERE", "LIKE":
+		bs, err := ioutil.ReadAll(buf)
+		if err != nil {
+			return nil, err
+		}
+
+		expr, err := parseExpr(string(bs))
+		if err != nil {
+			return nil, err
+		}
+
+		var filter sql.Expression
+		if strings.ToUpper(clause) == "LIKE" {
+			filter = expression.NewLike(
+				expression.NewUnresolvedColumn("collation"),
+				expr,
+			)
+		} else {
+			filter = expr
+		}
+
+		return plan.NewFilter(
+			filter,
+			plan.NewShowCollation(),
+		), nil
+	default:
+		return nil, errUnexpectedSyntax.New("one of: LIKE or WHERE", clause)
+	}
+}
+
 var fixSessionRegex = regexp.MustCompile(`(,\s*|(set|SET)\s+)(SESSION|session)\s+([a-zA-Z0-9_]+)\s*=`)
 var fixGlobalRegex = regexp.MustCompile(`(,\s*|(set|SET)\s+)(GLOBAL|global)\s+([a-zA-Z0-9_]+)\s*=`)
 

sql/parse/parse_test.go

@@ -945,6 +945,21 @@ var fixtures = map[string]sql.Node{
 		)},
 		plan.NewUnresolvedTable("dual", ""),
 	),
+	"SHOW COLLATION": plan.NewShowCollation(),
+	"SHOW COLLATION LIKE 'foo'": plan.NewFilter(
+		expression.NewLike(
+			expression.NewUnresolvedColumn("collation"),
+			expression.NewLiteral("foo", sql.Text),
+		),
+		plan.NewShowCollation(),
+	),
+	"SHOW COLLATION WHERE Charset = 'foo'": plan.NewFilter(
+		expression.NewEquals(
+			expression.NewUnresolvedColumn("charset"),
+			expression.NewLiteral("foo", sql.Text),
+		),
+		plan.NewShowCollation(),
+	),
 }
 
 func TestParse(t *testing.T) {

sql/plan/show_collation.go

@@ -0,0 +1,53 @@
+package plan
+
+import "gopkg.in/src-d/go-mysql-server.v0/sql"
+
+// ShowCollation shows all available collations.
+type ShowCollation struct{}
+
+var collationSchema = sql.Schema{
+	{Name: "Collation", Type: sql.Text},
+	{Name: "Charset", Type: sql.Text},
+	{Name: "Id", Type: sql.Int64},
+	{Name: "Default", Type: sql.Text},
+	{Name: "Compiled", Type: sql.Text},
+	{Name: "Sortlen", Type: sql.Int64},
+}
+
+// NewShowCollation creates a new ShowCollation node.
+func NewShowCollation() ShowCollation {
+	return ShowCollation{}
+}
+
+// Children implements the sql.Node interface.
+func (ShowCollation) Children() []sql.Node { return nil }
+
+func (ShowCollation) String() string { return "SHOW COLLATION" }
+
+// Resolved implements the sql.Node interface.
+func (ShowCollation) Resolved() bool { return true }
+
+// RowIter implements the sql.Node interface.
+func (ShowCollation) RowIter(ctx *sql.Context) (sql.RowIter, error) {
+	return sql.RowsToRowIter(sql.Row{
+		defaultCollation,
+		defaultCharacterSet,
+		int64(1),
+		"Yes",
+		"Yes",
+		int64(1),
+	}), nil
+}
+
+// Schema implements the sql.Node interface.
+func (ShowCollation) Schema() sql.Schema { return collationSchema }
+
+// TransformUp implements the sql.Node interface.
+func (ShowCollation) TransformUp(f sql.TransformNodeFunc) (sql.Node, error) {
+	return f(ShowCollation{})
+}
+
+// TransformExpressionsUp implements the sql.Node interface.
+func (ShowCollation) TransformExpressionsUp(f sql.TransformExprFunc) (sql.Node, error) {
+	return ShowCollation{}, nil
+}

sql/plan/showwarnings_test.go

@@ -12,9 +12,9 @@ func TestShowWarnings(t *testing.T) {
 	require := require.New(t)
 
 	ctx := sql.NewEmptyContext()
-	ctx.Session.Warn(&sql.Warning{"l1", "w1", 1})
-	ctx.Session.Warn(&sql.Warning{"l2", "w2", 2})
-	ctx.Session.Warn(&sql.Warning{"l4", "w3", 3})
+	ctx.Session.Warn(&sql.Warning{Level: "l1", Message: "w1", Code: 1})
+	ctx.Session.Warn(&sql.Warning{Level: "l2", Message: "w2", Code: 2})
+	ctx.Session.Warn(&sql.Warning{Level: "l4", Message: "w3", Code: 3})
 
 	sw := ShowWarnings(ctx.Session.Warnings())
 	require.True(sw.Resolved())