sql: add star (*) parsing and resolution. (#63)

Author: smola

README.md

@@ -53,7 +53,7 @@ gitql exposes the following tables:
 
 gitql supports a subset of the SQL standard, currently including:
 
-* `SELECT` (`*` not supported yet)
+* `SELECT`
 * `WHERE` (`=` only)
 * `ORDER BY` (with `ASC` and `DESC`)
 * `LIMIT`

cmd/gitql/query.go

@@ -95,7 +95,6 @@ func (c *CmdQuery) printQuery(schema sql.Schema, iter sql.RowIter) {
 	w := tablewriter.NewWriter(os.Stdout)
 	headers := []string{}
 	for _, f := range schema {
-		fmt.Printf("HEADER: %s\n", f.Name)
 		headers = append(headers, f.Name)
 	}
 	w.SetHeader(headers)

sql/analyzer/analyzer_test.go

@@ -52,6 +52,18 @@ func TestAnalyzer_Analyze(t *testing.T) {
 	assert.Nil(err)
 	assert.Equal(expected, analyzed)
 
+	notAnalyzed = plan.NewProject(
+		[]sql.Expression{expression.NewStar()},
+		plan.NewUnresolvedTable("mytable"),
+	)
+	analyzed, err = a.Analyze(notAnalyzed)
+	expected = plan.NewProject(
+		[]sql.Expression{expression.NewGetField(0, sql.Integer, "i")},
+		table,
+	)
+	assert.Nil(err)
+	assert.Equal(expected, analyzed)
+
 	notAnalyzed = plan.NewProject(
 		[]sql.Expression{
 			expression.NewAlias(

sql/analyzer/rules.go

@@ -9,6 +9,7 @@ import (
 var DefaultRules = []Rule{
 	{"resolve_tables", resolveTables},
 	{"resolve_columns", resolveColumns},
+	{"resolve_star", resolveStar},
 }
 
 func resolveTables(a *Analyzer, n sql.Node) sql.Node {
@@ -28,6 +29,33 @@ func resolveTables(a *Analyzer, n sql.Node) sql.Node {
 	})
 }
 
+func resolveStar(a *Analyzer, n sql.Node) sql.Node {
+	if n.Resolved() {
+		return n
+	}
+
+	p, ok := n.(*plan.Project)
+	if !ok {
+		return n
+	}
+
+	if len(p.Expressions) != 1 {
+		return n
+	}
+
+	if _, ok := p.Expressions[0].(*expression.Star); !ok {
+		return n
+	}
+
+	var exprs []sql.Expression
+	for i, e := range p.Child.Schema() {
+		gf := expression.NewGetField(i, e.Type, e.Name)
+		exprs = append(exprs, gf)
+	}
+
+	return plan.NewProject(exprs, p.Child)
+}
+
 func resolveColumns(a *Analyzer, n sql.Node) sql.Node {
 	if n.Resolved() {
 		return n

sql/plan/project.go

@@ -6,19 +6,19 @@ import (
 
 type Project struct {
 	UnaryNode
-	expressions []sql.Expression
+	Expressions []sql.Expression
 }
 
 func NewProject(expressions []sql.Expression, child sql.Node) *Project {
 	return &Project{
 		UnaryNode:   UnaryNode{child},
-		expressions: expressions,
+		Expressions: expressions,
 	}
 }
 
 func (p *Project) Schema() sql.Schema {
 	var s sql.Schema
-	for _, e := range p.expressions {
+	for _, e := range p.Expressions {
 		f := sql.Field{
 			Name: e.Name(),
 			Type: e.Type(),
@@ -33,7 +33,7 @@ func (p *Project) Resolved() bool {
 }
 
 func (p *Project) expressionsResolved() bool {
-	for _, e := range p.expressions {
+	for _, e := range p.Expressions {
 		if !e.Resolved() {
 			return false
 		}
@@ -51,15 +51,15 @@ func (p *Project) RowIter() (sql.RowIter, error) {
 
 func (p *Project) TransformUp(f func(sql.Node) sql.Node) sql.Node {
 	c := p.UnaryNode.Child.TransformUp(f)
-	n := NewProject(p.expressions, c)
+	n := NewProject(p.Expressions, c)
 
 	return f(n)
 }
 
 func (p *Project) TransformExpressionsUp(f func(sql.Expression) sql.Expression) sql.Node {
 	c := p.UnaryNode.Child.TransformExpressionsUp(f)
 	es := []sql.Expression{}
-	for _, e := range p.expressions {
+	for _, e := range p.Expressions {
 		te := e.TransformUp(f)
 		es = append(es, te)
 	}
@@ -78,7 +78,7 @@ func (i *iter) Next() (sql.Row, error) {
 	if err != nil {
 		return nil, err
 	}
-	return filterRow(i.p.expressions, childRow), nil
+	return filterRow(i.p.Expressions, childRow), nil
 }
 
 func filterRow(expressions []sql.Expression, row sql.Row) sql.Row {