go__parsing_demo/03-tree_walk_with_packages/stmt.go

package main

import (
	"fmt"
	"go/ast"
)

func parseStmt(loc string, s ast.Stmt) {
	switch s := s.(type) {
	case *ast.CaseClause:
		parseCaseClause(loc, s)
	case *ast.DeclStmt:
		parseDeclStmt(loc, s)
	case *ast.ExprStmt, *ast.AssignStmt, *ast.ReturnStmt,
		*ast.BranchStmt: // break, continue, fallthrough, goto,
		// fmt.Printf("%s/(%T)\n", loc, s)
	case *ast.IfStmt:
		parseIfStmt(loc, s)
	case *ast.RangeStmt:
		parseRangeStmt(loc, s)
	case *ast.TypeSwitchStmt:
		parseTypeSwitchStmt(loc, s)
	default:
		fmt.Printf("Unhandled type %T\n", s)
	}
}

func parseCaseClause(loc string, s *ast.CaseClause) {
	loc += "/case"
	if s.Body == nil {
		// fmt.Printf("%s/(nil case)\n", loc)
		return
	}
	for _, rs := range s.Body {
		parseStmt(loc, rs)
	}
}

func parseDeclStmt(loc string, s *ast.DeclStmt) {
	loc += "/decl"
	switch d := s.Decl.(type) {
	case *ast.GenDecl:
		parseGenDecl(loc, d)
	default:
		fmt.Printf("DeclStmt: %T\n", d)
	}
}

func parseIfStmt(loc string, s *ast.IfStmt) {
	loc += "/if"
	// fmt.Println(loc)
	if s.Body == nil {
		fmt.Printf("%s/(nil if)\n", loc)
	} else {
		thenLoc := loc + "/then"
		for _, rs := range s.Body.List {
			parseStmt(thenLoc, rs)
		}
	}
	if s.Else == nil {
		// fmt.Printf("%s/(nil else)\n", loc)
		return
	} else {
		elseLoc := loc + "/else"
		for _, rs := range s.Else.(*ast.BlockStmt).List {
			parseStmt(elseLoc, rs)
		}
	}
}

func parseRangeStmt(loc string, s *ast.RangeStmt) {
	loc += "/range"
	// fmt.Println(loc)
	if s.Body == nil {
		fmt.Printf("%s/(nil range)\n", loc)
		return
	}
	for _, rs := range s.Body.List {
		parseStmt(loc, rs)
	}
}

func parseTypeSwitchStmt(loc string, s *ast.TypeSwitchStmt) {
	loc += "/(type)"
	// fmt.Println(loc)
	if s.Body == nil {
		fmt.Printf("%s/(nil body)\n", loc)
		return
	}
	for _, clause := range s.Body.List {
		body := clause.(*ast.CaseClause).Body
		if body == nil {
			// fmt.Printf("%s/empty clause\n", loc)
			continue
		}
		for _, rs := range body {
			parseStmt(loc, rs)
		}
	}
}