Add an interpreter base for function creation

scripts/format_repo.sh

@@ -23,7 +23,7 @@ paths=`find . -maxdepth 1 -mindepth 1 ! -name ".idea" ! -name ".git" ! -name ".g
 
 goimports -w -local github.com/dolthub/doltgresql $paths
 
-bad_files=$(find $paths -name '*.go' | while read f; do
+bad_files=$(find $paths -name '*.go' ! -path ".idea/*" | while read f; do
     if [[ $(awk '/import \(/{flag=1;next}/\)/{flag=0}flag' < $f | egrep -c '$^') -gt 2 ]]; then
         echo $f
     fi

server/expression/init.go

@@ -0,0 +1,27 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expression
+
+import (
+	"github.com/dolthub/doltgresql/server/functions/framework"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// Init handles all setup needed for this package.
+func Init() {
+	framework.NewUnsafeLiteral = func(val any, t *pgtypes.DoltgresType) framework.LiteralInterface {
+		return NewUnsafeLiteral(val, t)
+	}
+}

server/functions/framework/catalog.go

@@ -52,6 +52,9 @@ func RegisterFunction(f FunctionInterface) {
 	case Function4:
 		name := strings.ToLower(f.Name)
 		Catalog[name] = append(Catalog[name], f)
+	case InterpretedFunction:
+		name := strings.ToLower(f.ID.FunctionName())
+		Catalog[name] = append(Catalog[name], f)
 	default:
 		panic("unhandled function type")
 	}

server/functions/framework/compiled_function.go

@@ -20,6 +20,7 @@ import (
 
 	cerrors "github.com/cockroachdb/errors"
 	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/analyzer"
 	"github.com/dolthub/go-mysql-server/sql/expression"
 	"gopkg.in/src-d/go-errors.v1"
 
@@ -46,15 +47,17 @@ type CompiledFunction struct {
 	overload      overloadMatch
 	originalTypes []*pgtypes.DoltgresType
 	callResolved  []*pgtypes.DoltgresType
+	runner        analyzer.StatementRunner
 	stashedErr    error
 }
 
 var _ sql.FunctionExpression = (*CompiledFunction)(nil)
 var _ sql.NonDeterministicExpression = (*CompiledFunction)(nil)
+var _ analyzer.Interpreter = (*CompiledFunction)(nil)
 
 // NewCompiledFunction returns a newly compiled function.
 func NewCompiledFunction(name string, args []sql.Expression, functions *Overloads, isOperator bool) *CompiledFunction {
-	return newCompiledFunctionInternal(name, args, functions, functions.overloadsForParams(len(args)), isOperator)
+	return newCompiledFunctionInternal(name, args, functions, functions.overloadsForParams(len(args)), isOperator, nil)
 }
 
 // newCompiledFunctionInternal is called internally, which skips steps that may have already been processed.
@@ -64,8 +67,16 @@ func newCompiledFunctionInternal(
 	overloads *Overloads,
 	fnOverloads []Overload,
 	isOperator bool,
+	runner analyzer.StatementRunner,
 ) *CompiledFunction {
-	c := &CompiledFunction{Name: name, Arguments: args, IsOperator: isOperator, overloads: overloads, fnOverloads: fnOverloads}
+	c := &CompiledFunction{
+		Name:        name,
+		Arguments:   args,
+		IsOperator:  isOperator,
+		overloads:   overloads,
+		fnOverloads: fnOverloads,
+		runner:      runner,
+	}
 	// First we'll analyze all the parameters.
 	originalTypes, err := c.analyzeParameters()
 	if err != nil {
@@ -292,6 +303,8 @@ func (c *CompiledFunction) Eval(ctx *sql.Context, row sql.Row) (interface{}, err
 		return f.Callable(ctx, ([4]*pgtypes.DoltgresType)(c.callResolved), args[0], args[1], args[2])
 	case Function4:
 		return f.Callable(ctx, ([5]*pgtypes.DoltgresType)(c.callResolved), args[0], args[1], args[2], args[3])
+	case InterpretedFunction:
+		return f.Call(ctx, c.runner, c.callResolved, args)
 	default:
 		return nil, cerrors.Errorf("unknown function type in CompiledFunction::Eval")
 	}
@@ -309,7 +322,13 @@ func (c *CompiledFunction) WithChildren(children ...sql.Expression) (sql.Express
 	}
 
 	// We have to re-resolve here, since the change in children may require it (e.g. we have more type info than we did)
-	return newCompiledFunctionInternal(c.Name, children, c.overloads, c.fnOverloads, c.IsOperator), nil
+	return newCompiledFunctionInternal(c.Name, children, c.overloads, c.fnOverloads, c.IsOperator, c.runner), nil
+}
+
+// SetStatementRunner implements the interface analyzer.Interpreter.
+func (c *CompiledFunction) SetStatementRunner(ctx *sql.Context, runner analyzer.StatementRunner) sql.Expression {
+	c.runner = runner
+	return c
 }
 
 // GetQuickFunction returns the QuickFunction form of this function, if it exists. If one does not exist, then this

server/functions/framework/intermediate_function.go

@@ -31,5 +31,5 @@ func (f IntermediateFunction) Compile(name string, parameters ...sql.Expression)
 	if f.Functions == nil {
 		return nil
 	}
-	return newCompiledFunctionInternal(name, parameters, f.Functions, f.AllOverloads, f.IsOperator)
+	return newCompiledFunctionInternal(name, parameters, f.Functions, f.AllOverloads, f.IsOperator, nil)
 }

server/functions/framework/interpreter.go

@@ -0,0 +1,170 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package framework
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/lib/pq"
+
+	"github.com/dolthub/doltgresql/core/id"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// InterpretedFunction is the implementation of functions created using PL/pgSQL. The created functions are converted to
+// a collection of operations, and an interpreter iterates over those operations to handle the logic.
+type InterpretedFunction struct {
+	ID                 id.Function
+	ReturnType         *pgtypes.DoltgresType
+	ParameterNames     []string
+	ParameterTypes     []*pgtypes.DoltgresType
+	Variadic           bool
+	IsNonDeterministic bool
+	Strict             bool
+	Labels             map[string]int
+	Statements         []InterpreterOperation
+}
+
+var _ FunctionInterface = InterpretedFunction{}
+
+// GetExpectedParameterCount implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) GetExpectedParameterCount() int {
+	return len(iFunc.ParameterTypes)
+}
+
+// GetName implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) GetName() string {
+	return iFunc.ID.FunctionName()
+}
+
+// GetParameters implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) GetParameters() []*pgtypes.DoltgresType {
+	return iFunc.ParameterTypes
+}
+
+// GetReturn implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) GetReturn() *pgtypes.DoltgresType {
+	return iFunc.ReturnType
+}
+
+// InternalID implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) InternalID() id.Id {
+	return iFunc.ID.AsId()
+}
+
+// IsStrict implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) IsStrict() bool {
+	return iFunc.Strict
+}
+
+// Return implements the interface plan.Interpreter.
+func (iFunc InterpretedFunction) Return(ctx *sql.Context) sql.Type {
+	return iFunc.ReturnType
+}
+
+// NonDeterministic implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) NonDeterministic() bool {
+	return iFunc.IsNonDeterministic
+}
+
+// VariadicIndex implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) VariadicIndex() int {
+	// TODO: implement variadic
+	return -1
+}
+
+// querySingleReturn handles queries that are supposed to return a single value.
+func (iFunc InterpretedFunction) querySingleReturn(ctx *sql.Context, stack InterpreterStack, stmt string, targetType *pgtypes.DoltgresType, bindings []string) (val any, err error) {
+	if len(bindings) > 0 {
+		for i, bindingName := range bindings {
+			variable := stack.GetVariable(bindingName)
+			if variable == nil {
+				return nil, fmt.Errorf("variable `%s` could not be found", bindingName)
+			}
+			formattedVar, err := variable.Type.FormatValue(variable.Value)
+			if err != nil {
+				return nil, err
+			}
+			switch variable.Type.TypCategory {
+			case pgtypes.TypeCategory_ArrayTypes, pgtypes.TypeCategory_StringTypes:
+				formattedVar = pq.QuoteLiteral(formattedVar)
+			}
+			stmt = strings.Replace(stmt, "$"+strconv.Itoa(i+1), formattedVar, 1)
+		}
+	}
+	sch, rowIter, _, err := stack.runner.QueryWithBindings(ctx, stmt, nil, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	rows, err := sql.RowIterToRows(ctx, rowIter)
+	if err != nil {
+		return nil, err
+	}
+	if len(sch) != 1 {
+		return nil, errors.New("expression does not result in a single value")
+	}
+	if len(rows) != 1 {
+		return nil, errors.New("expression returned multiple result sets")
+	}
+	if len(rows[0]) != 1 {
+		return nil, errors.New("expression returned multiple results")
+	}
+	if targetType == nil {
+		return rows[0][0], nil
+	}
+	fromType, ok := sch[0].Type.(*pgtypes.DoltgresType)
+	if !ok {
+		fromType, err = pgtypes.FromGmsTypeToDoltgresType(sch[0].Type)
+		if err != nil {
+			return nil, err
+		}
+	}
+	castFunc := GetAssignmentCast(fromType, targetType)
+	if castFunc == nil {
+		// TODO: try I/O casting
+		return nil, errors.New("no valid cast for return value")
+	}
+	return castFunc(ctx, rows[0][0], targetType)
+}
+
+// queryMultiReturn handles queries that may return multiple values over multiple rows.
+func (iFunc InterpretedFunction) queryMultiReturn(ctx *sql.Context, stack InterpreterStack, stmt string, bindings []string) (rowIter sql.RowIter, err error) {
+	if len(bindings) > 0 {
+		for i, bindingName := range bindings {
+			variable := stack.GetVariable(bindingName)
+			if variable == nil {
+				return nil, fmt.Errorf("variable `%s` could not be found", bindingName)
+			}
+			formattedVar, err := variable.Type.FormatValue(variable.Value)
+			if err != nil {
+				return nil, err
+			}
+			switch variable.Type.TypCategory {
+			case pgtypes.TypeCategory_ArrayTypes, pgtypes.TypeCategory_StringTypes:
+				formattedVar = pq.QuoteLiteral(formattedVar)
+			}
+			stmt = strings.Replace(stmt, "$"+strconv.Itoa(i+1), formattedVar, 1)
+		}
+	}
+	_, rowIter, _, err = stack.runner.QueryWithBindings(ctx, stmt, nil, nil, nil)
+	return rowIter, err
+}
+
+// enforceInterfaceInheritance implements the interface FunctionInterface.
+func (iFunc InterpretedFunction) enforceInterfaceInheritance(error) {}