neo-go/pkg/vm/compiler/analysis.go

package compiler

import (
	"go/ast"
	"go/constant"
	"go/types"
	"log"

	"golang.org/x/tools/go/loader"
)

// countGlobals counts the global variables in the program to add
// them with the stacksize of the function.
func countGlobals(f *ast.File) (i int64) {
	ast.Inspect(f, func(node ast.Node) bool {
		switch node.(type) {
		// Skip all functio declarations.
		case *ast.FuncDecl:
			return false
		// After skipping all funcDecls we are sure that each value spec
		// is a global declared variable or constant.
		case *ast.ValueSpec:
			i++
		}
		return true
	})
	return
}

// isIdentBool looks if the given ident is a boolean.
func isIdentBool(ident *ast.Ident) bool {
	return ident.Name == "true" || ident.Name == "false"
}

// makeBoolFromIdent creates a bool type from an *ast.Ident.
func makeBoolFromIdent(ident *ast.Ident, tinfo *types.Info) types.TypeAndValue {
	var b bool
	if ident.Name == "true" {
		b = true
	} else if ident.Name == "false" {
		b = false
	} else {
		log.Fatalf("givent identifier cannot be converted to a boolean => %s", ident.Name)
	}
	return types.TypeAndValue{
		Type:  tinfo.ObjectOf(ident).Type(),
		Value: constant.MakeBool(b),
	}
}

// resolveEntryPoint returns the function declaration of the entrypoint and the corresponding file.
func resolveEntryPoint(entry string, pkg *loader.PackageInfo) (*ast.FuncDecl, *ast.File) {
	var (
		main *ast.FuncDecl
		file *ast.File
	)
	for _, f := range pkg.Files {
		ast.Inspect(f, func(n ast.Node) bool {
			switch t := n.(type) {
			case *ast.FuncDecl:
				if t.Name.Name == entry {
					main = t
					file = f
					return false
				}
			}
			return true
		})
	}
	return main, file
}