/* * Public Domain Software * * I (Matthias Ladkau) am the author of the source code in this file. * I have placed the source code in this file in the public domain. * * For further information see: http://creativecommons.org/publicdomain/zero/1.0/ */ package parser import ( "bytes" "fmt" "strconv" "text/template" "devt.de/krotik/common/errorutil" "devt.de/krotik/common/stringutil" ) /* Map of AST nodes corresponding to lexer tokens */ var prettyPrinterMap map[string]*template.Template /* Map of nodes where the precedence might have changed because of parentheses */ var bracketPrecedenceMap map[string]bool func init() { prettyPrinterMap = map[string]*template.Template{ NodeSTRING: template.Must(template.New(NodeTRUE).Parse("{{.qval}}")), NodeNUMBER: template.Must(template.New(NodeTRUE).Parse("{{.val}}")), NodeIDENTIFIER: template.Must(template.New(NodeTRUE).Parse("{{.val}}")), // Constructed tokens // NodeSTATEMENTS - Special case (handled in code) /* NodeSTATEMENTS = "statements" // List of statements // Assignment statement NodeASSIGN = ":=" */ NodeASSIGN + "_2": template.Must(template.New(NodeMINUS).Parse("{{.c1}} := {{.c2}}")), // Arithmetic operators NodePLUS + "_1": template.Must(template.New(NodeMINUS).Parse("+{{.c1}}")), NodePLUS + "_2": template.Must(template.New(NodePLUS).Parse("{{.c1}} + {{.c2}}")), NodeMINUS + "_1": template.Must(template.New(NodeMINUS).Parse("-{{.c1}}")), NodeMINUS + "_2": template.Must(template.New(NodeMINUS).Parse("{{.c1}} - {{.c2}}")), NodeTIMES + "_2": template.Must(template.New(NodeTIMES).Parse("{{.c1}} * {{.c2}}")), NodeDIV + "_2": template.Must(template.New(NodeDIV).Parse("{{.c1}} / {{.c2}}")), NodeMODINT + "_2": template.Must(template.New(NodeMODINT).Parse("{{.c1}} % {{.c2}}")), NodeDIVINT + "_2": template.Must(template.New(NodeDIVINT).Parse("{{.c1}} // {{.c2}}")), // Boolean operators NodeOR + "_2": template.Must(template.New(NodeGEQ).Parse("{{.c1}} or {{.c2}}")), NodeAND + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} and {{.c2}}")), NodeNOT + "_1": template.Must(template.New(NodeNOT).Parse("not {{.c1}}")), // Condition operators NodeLIKE + "_2": template.Must(template.New(NodeGEQ).Parse("{{.c1}} like {{.c2}}")), NodeIN + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} in {{.c2}}")), NodeHASPREFIX + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} hasprefix {{.c2}}")), NodeHASSUFFIX + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} hassuffix {{.c2}}")), NodeNOTIN + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} notin {{.c2}}")), NodeGEQ + "_2": template.Must(template.New(NodeGEQ).Parse("{{.c1}} >= {{.c2}}")), NodeLEQ + "_2": template.Must(template.New(NodeLEQ).Parse("{{.c1}} <= {{.c2}}")), NodeNEQ + "_2": template.Must(template.New(NodeNEQ).Parse("{{.c1}} != {{.c2}}")), NodeEQ + "_2": template.Must(template.New(NodeEQ).Parse("{{.c1}} == {{.c2}}")), NodeGT + "_2": template.Must(template.New(NodeGT).Parse("{{.c1}} > {{.c2}}")), NodeLT + "_2": template.Must(template.New(NodeLT).Parse("{{.c1}} < {{.c2}}")), // Constants NodeTRUE: template.Must(template.New(NodeTRUE).Parse("true")), NodeFALSE: template.Must(template.New(NodeFALSE).Parse("false")), NodeNULL: template.Must(template.New(NodeNULL).Parse("null")), } bracketPrecedenceMap = map[string]bool{ NodePLUS: true, NodeMINUS: true, NodeAND: true, NodeOR: true, } } /* PrettyPrint produces pretty printed code from a given AST. */ func PrettyPrint(ast *ASTNode) (string, error) { var visit func(ast *ASTNode, level int) (string, error) visit = func(ast *ASTNode, level int) (string, error) { var buf bytes.Buffer var numChildren = len(ast.Children) tempKey := ast.Name tempParam := make(map[string]string) // First pretty print children if numChildren > 0 { for i, child := range ast.Children { res, err := visit(child, level+1) if err != nil { return "", err } if _, ok := bracketPrecedenceMap[child.Name]; ok && ast.binding > child.binding { // Put the expression in brackets iff (if and only if) the binding would // normally order things differently res = fmt.Sprintf("(%v)", res) } tempParam[fmt.Sprint("c", i+1)] = res } tempKey += fmt.Sprint("_", len(tempParam)) } // Handle special cases requiring children if ast.Name == NodeSTATEMENTS { // For statements just concat all children for i := 0; i < numChildren; i++ { buf.WriteString(stringutil.GenerateRollingString(" ", level*4)) buf.WriteString(tempParam[fmt.Sprint("c", i+1)]) buf.WriteString("\n") } return buf.String(), nil } if ast.Token != nil { // Adding node value to template parameters tempParam["val"] = ast.Token.Val tempParam["qval"] = strconv.Quote(ast.Token.Val) } // Retrieve the template temp, ok := prettyPrinterMap[tempKey] if !ok { return "", fmt.Errorf("Could not find template for %v (tempkey: %v)", ast.Name, tempKey) } // Use the children as parameters for template errorutil.AssertOk(temp.Execute(&buf, tempParam)) ret := buf.String() // Add meta data if len(ast.Meta) > 0 { for _, meta := range ast.Meta { if meta.Type() == MetaDataPreComment { ret = fmt.Sprintf("/*%v*/ %v", meta.Value(), ret) } else if meta.Type() == MetaDataPostComment { ret = fmt.Sprintf("%v #%v", ret, meta.Value()) } } } return ret, nil } return visit(ast, 0) }