diff options
Diffstat (limited to 'vendor/github.com/hashicorp/hcl/hcl/parser/parser.go')
| -rw-r--r-- | vendor/github.com/hashicorp/hcl/hcl/parser/parser.go | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/hcl/hcl/parser/parser.go b/vendor/github.com/hashicorp/hcl/hcl/parser/parser.go new file mode 100644 index 0000000..cc129b6 --- /dev/null +++ b/vendor/github.com/hashicorp/hcl/hcl/parser/parser.go @@ -0,0 +1,454 @@ +// Package parser implements a parser for HCL (HashiCorp Configuration +// Language) +package parser + +import ( + "errors" + "fmt" + "strings" + + "github.com/hashicorp/hcl/hcl/ast" + "github.com/hashicorp/hcl/hcl/scanner" + "github.com/hashicorp/hcl/hcl/token" +) + +type Parser struct { + sc *scanner.Scanner + + // Last read token + tok token.Token + commaPrev token.Token + + comments []*ast.CommentGroup + leadComment *ast.CommentGroup // last lead comment + lineComment *ast.CommentGroup // last line comment + + enableTrace bool + indent int + n int // buffer size (max = 1) +} + +func newParser(src []byte) *Parser { + return &Parser{ + sc: scanner.New(src), + } +} + +// Parse returns the fully parsed source and returns the abstract syntax tree. +func Parse(src []byte) (*ast.File, error) { + p := newParser(src) + return p.Parse() +} + +var errEofToken = errors.New("EOF token found") + +// Parse returns the fully parsed source and returns the abstract syntax tree. +func (p *Parser) Parse() (*ast.File, error) { + f := &ast.File{} + var err, scerr error + p.sc.Error = func(pos token.Pos, msg string) { + scerr = &PosError{Pos: pos, Err: errors.New(msg)} + } + + f.Node, err = p.objectList() + if scerr != nil { + return nil, scerr + } + if err != nil { + return nil, err + } + + f.Comments = p.comments + return f, nil +} + +func (p *Parser) objectList() (*ast.ObjectList, error) { + defer un(trace(p, "ParseObjectList")) + node := &ast.ObjectList{} + + for { + n, err := p.objectItem() + if err == errEofToken { + break // we are finished + } + + // we don't return a nil node, because might want to use already + // collected items. + if err != nil { + return node, err + } + + node.Add(n) + } + return node, nil +} + +func (p *Parser) consumeComment() (comment *ast.Comment, endline int) { + endline = p.tok.Pos.Line + + // count the endline if it's multiline comment, ie starting with /* + if len(p.tok.Text) > 1 && p.tok.Text[1] == '*' { + // don't use range here - no need to decode Unicode code points + for i := 0; i < len(p.tok.Text); i++ { + if p.tok.Text[i] == '\n' { + endline++ + } + } + } + + comment = &ast.Comment{Start: p.tok.Pos, Text: p.tok.Text} + p.tok = p.sc.Scan() + return +} + +func (p *Parser) consumeCommentGroup(n int) (comments *ast.CommentGroup, endline int) { + var list []*ast.Comment + endline = p.tok.Pos.Line + + for p.tok.Type == token.COMMENT && p.tok.Pos.Line <= endline+n { + var comment *ast.Comment + comment, endline = p.consumeComment() + list = append(list, comment) + } + + // add comment group to the comments list + comments = &ast.CommentGroup{List: list} + p.comments = append(p.comments, comments) + + return +} + +// objectItem parses a single object item +func (p *Parser) objectItem() (*ast.ObjectItem, error) { + defer un(trace(p, "ParseObjectItem")) + + keys, err := p.objectKey() + if len(keys) > 0 && err == errEofToken { + // We ignore eof token here since it is an error if we didn't + // receive a value (but we did receive a key) for the item. + err = nil + } + if len(keys) > 0 && err != nil && p.tok.Type == token.RBRACE { + // This is a strange boolean statement, but what it means is: + // We have keys with no value, and we're likely in an object + // (since RBrace ends an object). For this, we set err to nil so + // we continue and get the error below of having the wrong value + // type. + err = nil + + // Reset the token type so we don't think it completed fine. See + // objectType which uses p.tok.Type to check if we're done with + // the object. + p.tok.Type = token.EOF + } + if err != nil { + return nil, err + } + + o := &ast.ObjectItem{ + Keys: keys, + } + + if p.leadComment != nil { + o.LeadComment = p.leadComment + p.leadComment = nil + } + + switch p.tok.Type { + case token.ASSIGN: + o.Assign = p.tok.Pos + o.Val, err = p.object() + if err != nil { + return nil, err + } + case token.LBRACE: + o.Val, err = p.objectType() + if err != nil { + return nil, err + } + default: + keyStr := make([]string, 0, len(keys)) + for _, k := range keys { + keyStr = append(keyStr, k.Token.Text) + } + + return nil, fmt.Errorf( + "key '%s' expected start of object ('{') or assignment ('=')", + strings.Join(keyStr, " ")) + } + + // do a look-ahead for line comment + p.scan() + if len(keys) > 0 && o.Val.Pos().Line == keys[0].Pos().Line && p.lineComment != nil { + o.LineComment = p.lineComment + p.lineComment = nil + } + p.unscan() + return o, nil +} + +// objectKey parses an object key and returns a ObjectKey AST +func (p *Parser) objectKey() ([]*ast.ObjectKey, error) { + keyCount := 0 + keys := make([]*ast.ObjectKey, 0) + + for { + tok := p.scan() + switch tok.Type { + case token.EOF: + // It is very important to also return the keys here as well as + // the error. This is because we need to be able to tell if we + // did parse keys prior to finding the EOF, or if we just found + // a bare EOF. + return keys, errEofToken + case token.ASSIGN: + // assignment or object only, but not nested objects. this is not + // allowed: `foo bar = {}` + if keyCount > 1 { + return nil, &PosError{ + Pos: p.tok.Pos, + Err: fmt.Errorf("nested object expected: LBRACE got: %s", p.tok.Type), + } + } + + if keyCount == 0 { + return nil, &PosError{ + Pos: p.tok.Pos, + Err: errors.New("no object keys found!"), + } + } + + return keys, nil + case token.LBRACE: + // object + return keys, nil + case token.IDENT, token.STRING: + keyCount++ + keys = append(keys, &ast.ObjectKey{Token: p.tok}) + case token.ILLEGAL: + fmt.Println("illegal") + default: + return keys, &PosError{ + Pos: p.tok.Pos, + Err: fmt.Errorf("expected: IDENT | STRING | ASSIGN | LBRACE got: %s", p.tok.Type), + } + } + } +} + +// object parses any type of object, such as number, bool, string, object or +// list. +func (p *Parser) object() (ast.Node, error) { + defer un(trace(p, "ParseType")) + tok := p.scan() + + switch tok.Type { + case token.NUMBER, token.FLOAT, token.BOOL, token.STRING, token.HEREDOC: + return p.literalType() + case token.LBRACE: + return p.objectType() + case token.LBRACK: + return p.listType() + case token.COMMENT: + // implement comment + case token.EOF: + return nil, errEofToken + } + + return nil, &PosError{ + Pos: tok.Pos, + Err: fmt.Errorf("Unknown token: %+v", tok), + } +} + +// objectType parses an object type and returns a ObjectType AST +func (p *Parser) objectType() (*ast.ObjectType, error) { + defer un(trace(p, "ParseObjectType")) + + // we assume that the currently scanned token is a LBRACE + o := &ast.ObjectType{ + Lbrace: p.tok.Pos, + } + + l, err := p.objectList() + + // if we hit RBRACE, we are good to go (means we parsed all Items), if it's + // not a RBRACE, it's an syntax error and we just return it. + if err != nil && p.tok.Type != token.RBRACE { + return nil, err + } + + // If there is no error, we should be at a RBRACE to end the object + if p.tok.Type != token.RBRACE { + return nil, fmt.Errorf("object expected closing RBRACE got: %s", p.tok.Type) + } + + o.List = l + o.Rbrace = p.tok.Pos // advanced via parseObjectList + return o, nil +} + +// listType parses a list type and returns a ListType AST +func (p *Parser) listType() (*ast.ListType, error) { + defer un(trace(p, "ParseListType")) + + // we assume that the currently scanned token is a LBRACK + l := &ast.ListType{ + Lbrack: p.tok.Pos, + } + + needComma := false + for { + tok := p.scan() + switch tok.Type { + case token.NUMBER, token.FLOAT, token.STRING, token.HEREDOC: + if needComma { + return nil, &PosError{ + Pos: tok.Pos, + Err: fmt.Errorf("unexpected token: %s. Expecting %s", tok.Type, token.COMMA), + } + } + + node, err := p.literalType() + if err != nil { + return nil, err + } + + l.Add(node) + needComma = true + case token.COMMA: + // get next list item or we are at the end + // do a look-ahead for line comment + p.scan() + if p.lineComment != nil { + lit, ok := l.List[len(l.List)-1].(*ast.LiteralType) + if ok { + lit.LineComment = p.lineComment + l.List[len(l.List)-1] = lit + p.lineComment = nil + } + } + p.unscan() + + needComma = false + continue + case token.BOOL: + // TODO(arslan) should we support? not supported by HCL yet + case token.LBRACK: + // TODO(arslan) should we support nested lists? Even though it's + // written in README of HCL, it's not a part of the grammar + // (not defined in parse.y) + case token.RBRACK: + // finished + l.Rbrack = p.tok.Pos + return l, nil + default: + return nil, &PosError{ + Pos: tok.Pos, + Err: fmt.Errorf("unexpected token while parsing list: %s", tok.Type), + } + } + } +} + +// literalType parses a literal type and returns a LiteralType AST +func (p *Parser) literalType() (*ast.LiteralType, error) { + defer un(trace(p, "ParseLiteral")) + + return &ast.LiteralType{ + Token: p.tok, + }, nil +} + +// scan returns the next token from the underlying scanner. If a token has +// been unscanned then read that instead. In the process, it collects any +// comment groups encountered, and remembers the last lead and line comments. +func (p *Parser) scan() token.Token { + // If we have a token on the buffer, then return it. + if p.n != 0 { + p.n = 0 + return p.tok + } + + // Otherwise read the next token from the scanner and Save it to the buffer + // in case we unscan later. + prev := p.tok + p.tok = p.sc.Scan() + + if p.tok.Type == token.COMMENT { + var comment *ast.CommentGroup + var endline int + + // fmt.Printf("p.tok.Pos.Line = %+v prev: %d endline %d \n", + // p.tok.Pos.Line, prev.Pos.Line, endline) + if p.tok.Pos.Line == prev.Pos.Line { + // The comment is on same line as the previous token; it + // cannot be a lead comment but may be a line comment. + comment, endline = p.consumeCommentGroup(0) + if p.tok.Pos.Line != endline { + // The next token is on a different line, thus + // the last comment group is a line comment. + p.lineComment = comment + } + } + + // consume successor comments, if any + endline = -1 + for p.tok.Type == token.COMMENT { + comment, endline = p.consumeCommentGroup(1) + } + + if endline+1 == p.tok.Pos.Line && p.tok.Type != token.RBRACE { + switch p.tok.Type { + case token.RBRACE, token.RBRACK: + // Do not count for these cases + default: + // The next token is following on the line immediately after the + // comment group, thus the last comment group is a lead comment. + p.leadComment = comment + } + } + + } + + return p.tok +} + +// unscan pushes the previously read token back onto the buffer. +func (p *Parser) unscan() { + p.n = 1 +} + +// ---------------------------------------------------------------------------- +// Parsing support + +func (p *Parser) printTrace(a ...interface{}) { + if !p.enableTrace { + return + } + + const dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " + const n = len(dots) + fmt.Printf("%5d:%3d: ", p.tok.Pos.Line, p.tok.Pos.Column) + + i := 2 * p.indent + for i > n { + fmt.Print(dots) + i -= n + } + // i <= n + fmt.Print(dots[0:i]) + fmt.Println(a...) +} + +func trace(p *Parser, msg string) *Parser { + p.printTrace(msg, "(") + p.indent++ + return p +} + +// Usage pattern: defer un(trace(p, "...")) +func un(p *Parser) { + p.indent-- + p.printTrace(")") +} |