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helpers.go
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/
helpers.go
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// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
//
// 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 gas
import (
"fmt"
"go/ast"
"go/token"
"go/types"
"strconv"
)
// MatchCallByPackage ensures that the specified package is imported,
// adjusts the name for any aliases and ignores cases that are
// initialization only imports.
//
// Usage:
// node, matched := MatchCallByPackage(n, ctx, "math/rand", "Read")
//
func MatchCallByPackage(n ast.Node, c *Context, pkg string, names ...string) (*ast.CallExpr, bool) {
importedName, found := GetImportedName(pkg, c)
if !found {
return nil, false
}
if callExpr, ok := n.(*ast.CallExpr); ok {
packageName, callName, err := GetCallInfo(callExpr, c)
if err != nil {
return nil, false
}
if packageName == importedName {
for _, name := range names {
if callName == name {
return callExpr, true
}
}
}
}
return nil, false
}
// MatchCallByType ensures that the node is a call expression to a
// specific object type.
//
// Usage:
// node, matched := MatchCallByType(n, ctx, "bytes.Buffer", "WriteTo", "Write")
//
func MatchCallByType(n ast.Node, ctx *Context, requiredType string, calls ...string) (*ast.CallExpr, bool) {
if callExpr, ok := n.(*ast.CallExpr); ok {
typeName, callName, err := GetCallInfo(callExpr, ctx)
if err != nil {
return nil, false
}
if typeName == requiredType {
for _, call := range calls {
if call == callName {
return callExpr, true
}
}
}
}
return nil, false
}
// MatchCompLit will match an ast.CompositeLit based on the supplied type
func MatchCompLit(n ast.Node, ctx *Context, required string) *ast.CompositeLit {
if complit, ok := n.(*ast.CompositeLit); ok {
typeOf := ctx.Info.TypeOf(complit)
if typeOf.String() == required {
return complit
}
}
return nil
}
// GetInt will read and return an integer value from an ast.BasicLit
func GetInt(n ast.Node) (int64, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.INT {
return strconv.ParseInt(node.Value, 0, 64)
}
return 0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetFloat will read and return a float value from an ast.BasicLit
func GetFloat(n ast.Node) (float64, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.FLOAT {
return strconv.ParseFloat(node.Value, 64)
}
return 0.0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetChar will read and return a char value from an ast.BasicLit
func GetChar(n ast.Node) (byte, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.CHAR {
return node.Value[0], nil
}
return 0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetString will read and return a string value from an ast.BasicLit
func GetString(n ast.Node) (string, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.STRING {
return strconv.Unquote(node.Value)
}
return "", fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetCallObject returns the object and call expression and associated
// object for a given AST node. nil, nil will be returned if the
// object cannot be resolved.
func GetCallObject(n ast.Node, ctx *Context) (*ast.CallExpr, types.Object) {
switch node := n.(type) {
case *ast.CallExpr:
switch fn := node.Fun.(type) {
case *ast.Ident:
return node, ctx.Info.Uses[fn]
case *ast.SelectorExpr:
return node, ctx.Info.Uses[fn.Sel]
}
}
return nil, nil
}
// GetCallInfo returns the package or type and name associated with a
// call expression.
func GetCallInfo(n ast.Node, ctx *Context) (string, string, error) {
switch node := n.(type) {
case *ast.CallExpr:
switch fn := node.Fun.(type) {
case *ast.SelectorExpr:
switch expr := fn.X.(type) {
case *ast.Ident:
if expr.Obj != nil && expr.Obj.Kind == ast.Var {
t := ctx.Info.TypeOf(expr)
if t != nil {
return t.String(), fn.Sel.Name, nil
}
return "undefined", fn.Sel.Name, fmt.Errorf("missing type info")
}
return expr.Name, fn.Sel.Name, nil
}
case *ast.Ident:
return ctx.Pkg.Name(), fn.Name, nil
}
}
return "", "", fmt.Errorf("unable to determine call info")
}
// GetImportedName returns the name used for the package within the
// code. It will resolve aliases and ignores initalization only imports.
func GetImportedName(path string, ctx *Context) (string, bool) {
importName, imported := ctx.Imports.Imported[path]
if !imported {
return "", false
}
if _, initonly := ctx.Imports.InitOnly[path]; initonly {
return "", false
}
if alias, ok := ctx.Imports.Aliased[path]; ok {
importName = alias
}
return importName, true
}
// GetImportPath resolves the full import path of an identifer based on
// the imports in the current context.
func GetImportPath(name string, ctx *Context) (string, bool) {
for path := range ctx.Imports.Imported {
if imported, ok := GetImportedName(path, ctx); ok && imported == name {
return path, true
}
}
return "", false
}
// GetLocation returns the filename and line number of an ast.Node
func GetLocation(n ast.Node, ctx *Context) (string, int) {
fobj := ctx.FileSet.File(n.Pos())
return fobj.Name(), fobj.Line(n.Pos())
}