// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the exported entry points for invoking the parser.

package parser

import (
	
	
	
	
	
	
	
	
	
)

// If src != nil, readSource converts src to a []byte if possible;
// otherwise it returns an error. If src == nil, readSource returns
// the result of reading the file specified by filename.
//
func readSource( string,  interface{}) ([]byte, error) {
	if  != nil {
		switch s := .(type) {
		case string:
			return []byte(), nil
		case []byte:
			return , nil
		case *bytes.Buffer:
			// is io.Reader, but src is already available in []byte form
			if  != nil {
				return .Bytes(), nil
			}
		case io.Reader:
			return io.ReadAll()
		}
		return nil, errors.New("invalid source")
	}
	return os.ReadFile()
}

// A Mode value is a set of flags (or 0).
// They control the amount of source code parsed and other optional
// parser functionality.
//
type Mode uint

const (
	PackageClauseOnly    Mode             = 1 << iota // stop parsing after package clause
	ImportsOnly                                       // stop parsing after import declarations
	ParseComments                                     // parse comments and add them to AST
	Trace                                             // print a trace of parsed productions
	DeclarationErrors                                 // report declaration errors
	SpuriousErrors                                    // same as AllErrors, for backward-compatibility
	SkipObjectResolution                              // don't resolve identifiers to objects - see ParseFile
	AllErrors            = SpuriousErrors             // report all errors (not just the first 10 on different lines)
)

// ParseFile parses the source code of a single Go source file and returns
// the corresponding ast.File node. The source code may be provided via
// the filename of the source file, or via the src parameter.
//
// If src != nil, ParseFile parses the source from src and the filename is
// only used when recording position information. The type of the argument
// for the src parameter must be string, []byte, or io.Reader.
// If src == nil, ParseFile parses the file specified by filename.
//
// The mode parameter controls the amount of source text parsed and other
// optional parser functionality. If the SkipObjectResolution mode bit is set,
// the object resolution phase of parsing will be skipped, causing File.Scope,
// File.Unresolved, and all Ident.Obj fields to be nil.
//
// Position information is recorded in the file set fset, which must not be
// nil.
//
// If the source couldn't be read, the returned AST is nil and the error
// indicates the specific failure. If the source was read but syntax
// errors were found, the result is a partial AST (with ast.Bad* nodes
// representing the fragments of erroneous source code). Multiple errors
// are returned via a scanner.ErrorList which is sorted by source position.
//
func ( *token.FileSet,  string,  interface{},  Mode) ( *ast.File,  error) {
	if  == nil {
		panic("parser.ParseFile: no token.FileSet provided (fset == nil)")
	}

	// get source
	,  := readSource(, )
	if  != nil {
		return nil, 
	}

	var  parser
	defer func() {
		if  := recover();  != nil {
			// resume same panic if it's not a bailout
			if ,  := .(bailout); ! {
				panic()
			}
		}

		// set result values
		if  == nil {
			// source is not a valid Go source file - satisfy
			// ParseFile API and return a valid (but) empty
			// *ast.File
			 = &ast.File{
				Name:  new(ast.Ident),
				Scope: ast.NewScope(nil),
			}
		}

		.errors.Sort()
		 = .errors.Err()
	}()

	// parse source
	.init(, , , )
	 = .parseFile()

	return
}

// ParseDir calls ParseFile for all files with names ending in ".go" in the
// directory specified by path and returns a map of package name -> package
// AST with all the packages found.
//
// If filter != nil, only the files with fs.FileInfo entries passing through
// the filter (and ending in ".go") are considered. The mode bits are passed
// to ParseFile unchanged. Position information is recorded in fset, which
// must not be nil.
//
// If the directory couldn't be read, a nil map and the respective error are
// returned. If a parse error occurred, a non-nil but incomplete map and the
// first error encountered are returned.
//
func ( *token.FileSet,  string,  func(fs.FileInfo) bool,  Mode) ( map[string]*ast.Package,  error) {
	,  := os.ReadDir()
	if  != nil {
		return nil, 
	}

	 = make(map[string]*ast.Package)
	for ,  := range  {
		if .IsDir() || !strings.HasSuffix(.Name(), ".go") {
			continue
		}
		if  != nil {
			,  := .Info()
			if  != nil {
				return nil, 
			}
			if !() {
				continue
			}
		}
		 := filepath.Join(, .Name())
		if ,  := ParseFile(, , nil, );  == nil {
			 := .Name.Name
			,  := []
			if ! {
				 = &ast.Package{
					Name:  ,
					Files: make(map[string]*ast.File),
				}
				[] = 
			}
			.Files[] = 
		} else if  == nil {
			 = 
		}
	}

	return
}

// ParseExprFrom is a convenience function for parsing an expression.
// The arguments have the same meaning as for ParseFile, but the source must
// be a valid Go (type or value) expression. Specifically, fset must not
// be nil.
//
// If the source couldn't be read, the returned AST is nil and the error
// indicates the specific failure. If the source was read but syntax
// errors were found, the result is a partial AST (with ast.Bad* nodes
// representing the fragments of erroneous source code). Multiple errors
// are returned via a scanner.ErrorList which is sorted by source position.
//
func ( *token.FileSet,  string,  interface{},  Mode) ( ast.Expr,  error) {
	if  == nil {
		panic("parser.ParseExprFrom: no token.FileSet provided (fset == nil)")
	}

	// get source
	,  := readSource(, )
	if  != nil {
		return nil, 
	}

	var  parser
	defer func() {
		if  := recover();  != nil {
			// resume same panic if it's not a bailout
			if ,  := .(bailout); ! {
				panic()
			}
		}
		.errors.Sort()
		 = .errors.Err()
	}()

	// parse expr
	.init(, , , )
	 = .parseRhsOrType()

	// If a semicolon was inserted, consume it;
	// report an error if there's more tokens.
	if .tok == token.SEMICOLON && .lit == "\n" {
		.next()
	}
	.expect(token.EOF)

	return
}

// ParseExpr is a convenience function for obtaining the AST of an expression x.
// The position information recorded in the AST is undefined. The filename used
// in error messages is the empty string.
//
// If syntax errors were found, the result is a partial AST (with ast.Bad* nodes
// representing the fragments of erroneous source code). Multiple errors are
// returned via a scanner.ErrorList which is sorted by source position.
//
func ( string) (ast.Expr, error) {
	return ParseExprFrom(token.NewFileSet(), "", []byte(), 0)
}