first pass at sqlc.nembed

Author: nickjackson

internal/compiler/parse.go

@@ -13,6 +13,7 @@ import (
 	"github.com/sqlc-dev/sqlc/internal/source"
 	"github.com/sqlc-dev/sqlc/internal/sql/ast"
 	"github.com/sqlc-dev/sqlc/internal/sql/astutils"
+	"github.com/sqlc-dev/sqlc/internal/sql/catalog"
 	"github.com/sqlc-dev/sqlc/internal/sql/rewrite"
 	"github.com/sqlc-dev/sqlc/internal/sql/validate"
 )
@@ -99,6 +100,11 @@ func (c *Compiler) parseQuery(stmt ast.Node, src string, o opts.Parser) (*Query,
 	if err != nil {
 		return nil, err
 	}
+
+	if err := buildNullTables(embeds, c.catalog); err != nil {
+		return nil, err
+	}
+
 	cols, err := c.outputColumns(qc, raw.Stmt)
 	if err != nil {
 		return nil, err
@@ -181,3 +187,50 @@ func uniqueParamRefs(in []paramRef, dollar bool) []paramRef {
 	}
 	return o
 }
+
+// buildNullTables adds additional tables to the catalog for nullable embeds
+func buildNullTables(embeds rewrite.EmbedSet, c *catalog.Catalog) error {
+	for _, emb := range embeds {
+		if !emb.Nullable {
+			continue
+		}
+
+		schema, table, err := c.GetSchemaTable(emb.Table)
+		if err != nil {
+			return err
+		}
+
+		emb.Table = &ast.TableName{
+			Catalog: table.Rel.Catalog,
+			Schema:  table.Rel.Schema,
+			Name:    "null_" + table.Rel.Name,
+		}
+
+		// skip if null table already exists
+		if table, _ := c.GetTable(emb.Table); table.Rel != nil {
+			continue
+		}
+
+		nullTable := &catalog.Table{
+			Rel:     emb.Table,
+			Columns: []*catalog.Column{},
+		}
+
+		for _, c := range table.Columns {
+			nullTable.Columns = append(nullTable.Columns, &catalog.Column{
+				Name:       c.Name,
+				Type:       c.Type,
+				IsNotNull:  false,
+				IsUnsigned: c.IsUnsigned,
+				IsArray:    c.IsArray,
+				ArrayDims:  c.ArrayDims,
+				Comment:    c.Comment,
+				Length:     c.Length,
+			})
+		}
+
+		schema.Tables = append(schema.Tables, nullTable)
+	}
+
+	return nil
+}

internal/sql/catalog/public.go

@@ -131,3 +131,12 @@ func (c *Catalog) GetTable(rel *ast.TableName) (Table, error) {
 		return *table, err
 	}
 }
+
+func (c *Catalog) GetSchemaTable(rel *ast.TableName) (*Schema, *Table, error) {
+	schema, table, err := c.getTable(rel)
+	if table == nil {
+		return nil, nil, err
+	} else {
+		return schema, table, err
+	}
+}

internal/sql/rewrite/embeds.go

@@ -7,15 +7,19 @@ import (
 	"github.com/sqlc-dev/sqlc/internal/sql/astutils"
 )
 
-// Embed is an instance of `sqlc.embed(param)`
+// Embed is an instance of `sqlc.embed(param)` or `sqlc.nembed(param)`
 type Embed struct {
-	Table *ast.TableName
-	param string
-	Node  *ast.ColumnRef
+	Table    *ast.TableName
+	param    string
+	Node     *ast.ColumnRef
+	Nullable bool
 }
 
 // Orig string to replace
 func (e Embed) Orig() string {
+	if e.Nullable {
+		return fmt.Sprintf("sqlc.nembed(%s)", e.param)
+	}
 	return fmt.Sprintf("sqlc.embed(%s)", e.param)
 }
 
@@ -61,9 +65,10 @@ func Embeds(raw *ast.RawStmt) (*ast.RawStmt, EmbedSet) {
 			}
 
 			embeds = append(embeds, &Embed{
-				Table: &ast.TableName{Name: param},
-				param: param,
-				Node:  node,
+				Table:    &ast.TableName{Name: param},
+				param:    param,
+				Node:     node,
+				Nullable: fun.Func.Name == "nembed",
 			})
 
 			cr.Replace(node)
@@ -86,6 +91,6 @@ func isEmbed(node ast.Node) bool {
 		return false
 	}
 
-	isValid := call.Func.Schema == "sqlc" && call.Func.Name == "embed"
+	isValid := call.Func.Schema == "sqlc" && (call.Func.Name == "embed" || call.Func.Name == "nembed")
 	return isValid
 }

internal/sql/validate/func_call.go

@@ -34,7 +34,7 @@ func (v *funcCallVisitor) Visit(node ast.Node) astutils.Visitor {
 	// Custom validation for sqlc.arg, sqlc.narg and sqlc.slice
 	// TODO: Replace this once type-checking is implemented
 	if fn.Schema == "sqlc" {
-		if !(fn.Name == "arg" || fn.Name == "narg" || fn.Name == "slice" || fn.Name == "embed") {
+		if !(fn.Name == "arg" || fn.Name == "narg" || fn.Name == "slice" || fn.Name == "embed" || fn.Name == "nembed") {
 			v.err = sqlerr.FunctionNotFound("sqlc." + fn.Name)
 			return nil
 		}