go[BREAKING CHANGE]: Overhaul naming of all the node types

This is in preparation for bootstrapping the go parser from the
grammar.

The first rename was in the `values.go` module.  The `Value` prefix
was stripped from {Value}String, {Value}Sequence, {Value}Node, and
{Value}Error.  The idea is to bolt this module into the final parser.

The above rename caused a collision between the `Node` interface in
the `grammar_ast.go` module.  Then this interface was renamed to
`AstNode`.

A mostly no-op change for now is that the prelude in go was split up
in its own file `prelude.go.in`.

Author: clarete

go/base_parser.go

@@ -25,7 +25,7 @@ type BaseParser struct {
 	predStkCnt int
 	labelMsgs  map[string]string
 	stacktrace []TracerSpan
-	actionFns  map[string]func(*ValueNode) (Value, error)
+	actionFns  map[string]func(*Node) (Value, error)
 }
 
 // Location returns in which line/column/cursor the parser's input is currently in
@@ -72,14 +72,14 @@ func (p *BaseParser) SetLabelMessages(m map[string]string) {
 	p.labelMsgs = m
 }
 
-func (p *BaseParser) SetAction(name string, fn func(*ValueNode) (Value, error)) {
+func (p *BaseParser) SetAction(name string, fn func(*Node) (Value, error)) {
 	if p.actionFns == nil {
-		p.actionFns = map[string]func(*ValueNode) (Value, error){}
+		p.actionFns = map[string]func(*Node) (Value, error){}
 	}
 	p.actionFns[name] = fn
 }
 
-func (p *BaseParser) RunAction(name string, node *ValueNode) (Value, error) {
+func (p *BaseParser) RunAction(name string, node *Node) (Value, error) {
 	action, ok := p.actionFns[name]
 	if !ok {
 		return node, nil
@@ -193,7 +193,7 @@ func (p *BaseParser) NewError(exp, msg string, span Span) error {
 		Expected:   exp,
 		Message:    msg,
 		// ErrSpan:    errSpan,
-		Span:       span,
+		Span: span,
 	}
 	return e
 }

go/gen_go.go

@@ -2,6 +2,7 @@ package langlang
 
 import (
 	"bytes"
+	_ "embed"
 	"fmt"
 	"strings"
 	"text/template"
@@ -22,7 +23,7 @@ type GenGoOptions struct {
 	ParserBase  string
 }
 
-func GenGo(node Node, opt GenGoOptions) (string, error) {
+func GenGo(node AstNode, opt GenGoOptions) (string, error) {
 	g := newGoCodeEmitter(opt)
 	g.writePrelude()
 	g.visit(node)
@@ -35,116 +36,8 @@ type tmplRenderOpts struct {
 	ParserName  string
 }
 
-var prelude string = `package {{.PackageName}}
-
-// This is an autogenerated file. Check your build system and find the
-// grammar to edit instead of editing this file directly, unless
-// you're fine with changes getting erased.
-
-import (
-	"fmt"
-
-	"github.com/clarete/langlang/go"
-)
-
-type {{.ParserName}} struct {
-	langlang.BaseParser
-	captureSpaces  bool
-	predicateLevel int
-	printTraceback bool
-	recoveryTable  map[string]langlang.ParserFn[langlang.Value]
-}
-
-func (p *{{.ParserName}}) SetCaptureSpaces(v bool) {
-	p.captureSpaces = v
-}
-
-func (p *{{.ParserName}}) SetPrintTraceback(v bool) {
-	p.printTraceback = v
-}
-
-func (p *{{.ParserName}}) parseAny() (langlang.Value, error) {
-	start := p.Location()
-	r, err := p.Any()
-	if err != nil {
-		var zero langlang.Value
-		return zero, err
-	}
-	return langlang.NewValueString(string(r), langlang.NewSpan(start, p.Location())), nil
-}
-
-func (p *{{.ParserName}}) parseRange(left, right rune) (langlang.Value, error) {
-	start := p.Location()
-	r, err := p.ExpectRange(left, right)
-	if err != nil {
-		var zero langlang.Value
-		return zero, err
-	}
-	return langlang.NewValueString(string(r), langlang.NewSpan(start, p.Location())), nil
-}
-
-func (p *{{.ParserName}}) parseLiteral(literal string) (langlang.Value, error) {
-	start := p.Location()
-	r, err := p.ExpectLiteral(literal)
-	if err != nil {
-		var zero langlang.Value
-		return zero, err
-	}
-	return langlang.NewValueString(r, langlang.NewSpan(start, p.Location())), nil
-}
-
-func (p *{{.ParserName}}) parseSpacing() (langlang.Value, error) {
-	start := p.Location()
-	v, err := langlang.ZeroOrMore(p, func(p langlang.Parser) (rune, error) {
-		return langlang.ChoiceRune(p, []rune{' ', '\t', '\r', '\n'})
-	})
-	if err != nil {
-		return nil, err
-	}
-	if !p.captureSpaces {
-		return nil, nil
-	}
-	r := string(v)
-	if len(r) == 0 {
-		return nil, nil
-	}
-	s := langlang.NewValueString(r, langlang.NewSpan(start, p.Location()))
-	return langlang.NewValueNode("Spacing", s, langlang.NewSpan(start, p.Location())), nil
-}
-
-func (p *{{.ParserName}}) ParseEOF() (langlang.Value, error) {
-	return (func(p langlang.Parser) (langlang.Value, error) {
-		var (
-			start = p.Location()
-			items []langlang.Value
-			item  langlang.Value
-			err   error
-		)
-		item, err = langlang.Not(p, func(p langlang.Parser) (langlang.Value, error) {
-			return p.(*{{.ParserName}}).parseAny()
-		})
-		if err != nil {
-			return nil, err
-		}
-		if item != nil {
-			items = append(items, item)
-		}
-		return p.(*{{.ParserName}}).wrapSeq(items, langlang.NewSpan(start, p.Location())), nil
-	}(p))
-}
-
-func (p *{{.ParserName}}) wrapSeq(items []langlang.Value, span langlang.Span) langlang.Value {
-	switch len(items) {
-	case 0:
-		return nil
-	case 1:
-		return items[0]
-	default:
-		return langlang.NewValueSequence(items, span)
-	}
-}
-
-`
+//go:embed prelude.go.in
+var goPrelude string
 
 func newGoCodeEmitter(opt GenGoOptions) *goCodeEmitter {
 	return &goCodeEmitter{
@@ -155,7 +48,7 @@ func newGoCodeEmitter(opt GenGoOptions) *goCodeEmitter {
 	}
 }
 
-func (g *goCodeEmitter) visit(node Node) {
+func (g *goCodeEmitter) visit(node AstNode) {
 	switch n := node.(type) {
 	case *GrammarNode:
 		g.visitGrammarNode(n)
@@ -240,7 +133,7 @@ func (g *goCodeEmitter) visitDefinitionNode(n *DefinitionNode) {
 	g.parser.indent()
 
 	g.parser.writei(fmt.Sprintf("\"%s\",\n", n.Name))
-	g.parser.writei(fmt.Sprintf("langlang.NewValueNode(\"%s\", item, langlang.NewSpan(start, p.Location())),\n", n.Name))
+	g.parser.writei(fmt.Sprintf("langlang.NewNode(\"%s\", item, langlang.NewSpan(start, p.Location())),\n", n.Name))
 
 	g.parser.unindent()
 	g.parser.writei(")\n")
@@ -515,7 +408,7 @@ func (g *goCodeEmitter) visitAnyNode() {
 // Utilities to write data into the output buffer
 
 func (g *goCodeEmitter) writePrelude() {
-	g.parser.write(prelude)
+	g.parser.write(goPrelude)
 }
 
 func (g *goCodeEmitter) writeConstructor() {
@@ -541,7 +434,7 @@ func (g *goCodeEmitter) writeConstructor() {
 			g.parser.writei("item, err := p.(*{{.ParserName}})")
 			fmt.Fprintf(g.parser.buffer, ".Parse%s()\n", label)
 			g.writeIfErr()
-			g.parser.writei("return langlang.NewValueError")
+			g.parser.writei("return langlang.NewError")
 			fmt.Fprintf(g.parser.buffer, "(\"%s\", item, langlang.NewSpan(start, p.Location())), nil\n", label)
 
 			g.parser.unindent()
@@ -568,12 +461,12 @@ func (g *goCodeEmitter) writeSeqOrNode() {
 
 	g.parser.writei("default:\n")
 	g.parser.indent()
-	g.parser.writei("return langlang.NewValueSequence(items, langlang.NewSpan(start, p.Location())), nil\n")
+	g.parser.writei("return langlang.NewSequence(items, langlang.NewSpan(start, p.Location())), nil\n")
 	g.parser.unindent()
 	g.parser.writei("}\n")
 }
 
-func (g *goCodeEmitter) writeExprFn(expr Node) {
+func (g *goCodeEmitter) writeExprFn(expr AstNode) {
 	g.parser.writei("func(p langlang.Parser) (langlang.Value, error) {\n")
 	g.parser.indent()