mirror of
https://github.com/rocky-linux/peridot.git
synced 2024-12-30 14:00:57 +00:00
350 lines
8.4 KiB
Go
350 lines
8.4 KiB
Go
package ini
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import (
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"fmt"
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"io"
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)
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// ParseState represents the current state of the parser.
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type ParseState uint
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// State enums for the parse table
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const (
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InvalidState ParseState = iota
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// stmt -> value stmt'
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StatementState
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// stmt' -> MarkComplete | op stmt
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StatementPrimeState
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// value -> number | string | boolean | quoted_string
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ValueState
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// section -> [ section'
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OpenScopeState
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// section' -> value section_close
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SectionState
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// section_close -> ]
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CloseScopeState
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// SkipState will skip (NL WS)+
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SkipState
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// SkipTokenState will skip any token and push the previous
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// state onto the stack.
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SkipTokenState
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// comment -> # comment' | ; comment'
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// comment' -> MarkComplete | value
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CommentState
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// MarkComplete state will complete statements and move that
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// to the completed AST list
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MarkCompleteState
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// TerminalState signifies that the tokens have been fully parsed
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TerminalState
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)
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// parseTable is a state machine to dictate the grammar above.
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var parseTable = map[ASTKind]map[TokenType]ParseState{
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ASTKindStart: {
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TokenLit: StatementState,
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TokenSep: OpenScopeState,
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TokenWS: SkipTokenState,
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TokenNL: SkipTokenState,
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TokenComment: CommentState,
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TokenNone: TerminalState,
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},
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ASTKindCommentStatement: {
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TokenLit: StatementState,
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TokenSep: OpenScopeState,
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TokenWS: SkipTokenState,
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TokenNL: SkipTokenState,
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TokenComment: CommentState,
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TokenNone: MarkCompleteState,
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},
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ASTKindExpr: {
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TokenOp: StatementPrimeState,
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TokenLit: ValueState,
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TokenSep: OpenScopeState,
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TokenWS: ValueState,
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TokenNL: SkipState,
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TokenComment: CommentState,
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TokenNone: MarkCompleteState,
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},
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ASTKindEqualExpr: {
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TokenLit: ValueState,
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TokenSep: ValueState,
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TokenOp: ValueState,
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TokenWS: SkipTokenState,
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TokenNL: SkipState,
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TokenNone: SkipState,
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},
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ASTKindStatement: {
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TokenLit: SectionState,
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TokenSep: CloseScopeState,
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TokenWS: SkipTokenState,
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TokenNL: SkipTokenState,
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TokenComment: CommentState,
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TokenNone: MarkCompleteState,
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},
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ASTKindExprStatement: {
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TokenLit: ValueState,
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TokenSep: ValueState,
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TokenOp: ValueState,
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TokenWS: ValueState,
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TokenNL: MarkCompleteState,
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TokenComment: CommentState,
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TokenNone: TerminalState,
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TokenComma: SkipState,
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},
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ASTKindSectionStatement: {
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TokenLit: SectionState,
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TokenOp: SectionState,
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TokenSep: CloseScopeState,
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TokenWS: SectionState,
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TokenNL: SkipTokenState,
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},
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ASTKindCompletedSectionStatement: {
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TokenWS: SkipTokenState,
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TokenNL: SkipTokenState,
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TokenLit: StatementState,
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TokenSep: OpenScopeState,
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TokenComment: CommentState,
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TokenNone: MarkCompleteState,
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},
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ASTKindSkipStatement: {
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TokenLit: StatementState,
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TokenSep: OpenScopeState,
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TokenWS: SkipTokenState,
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TokenNL: SkipTokenState,
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TokenComment: CommentState,
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TokenNone: TerminalState,
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},
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}
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// ParseAST will parse input from an io.Reader using
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// an LL(1) parser.
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func ParseAST(r io.Reader) ([]AST, error) {
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lexer := iniLexer{}
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tokens, err := lexer.Tokenize(r)
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if err != nil {
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return []AST{}, err
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}
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return parse(tokens)
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}
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// ParseASTBytes will parse input from a byte slice using
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// an LL(1) parser.
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func ParseASTBytes(b []byte) ([]AST, error) {
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lexer := iniLexer{}
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tokens, err := lexer.tokenize(b)
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if err != nil {
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return []AST{}, err
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}
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return parse(tokens)
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}
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func parse(tokens []Token) ([]AST, error) {
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start := Start
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stack := newParseStack(3, len(tokens))
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stack.Push(start)
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s := newSkipper()
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loop:
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for stack.Len() > 0 {
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k := stack.Pop()
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var tok Token
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if len(tokens) == 0 {
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// this occurs when all the tokens have been processed
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// but reduction of what's left on the stack needs to
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// occur.
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tok = emptyToken
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} else {
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tok = tokens[0]
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}
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step := parseTable[k.Kind][tok.Type()]
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if s.ShouldSkip(tok) {
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// being in a skip state with no tokens will break out of
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// the parse loop since there is nothing left to process.
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if len(tokens) == 0 {
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break loop
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}
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// if should skip is true, we skip the tokens until should skip is set to false.
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step = SkipTokenState
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}
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switch step {
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case TerminalState:
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// Finished parsing. Push what should be the last
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// statement to the stack. If there is anything left
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// on the stack, an error in parsing has occurred.
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if k.Kind != ASTKindStart {
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stack.MarkComplete(k)
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}
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break loop
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case SkipTokenState:
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// When skipping a token, the previous state was popped off the stack.
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// To maintain the correct state, the previous state will be pushed
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// onto the stack.
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stack.Push(k)
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case StatementState:
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if k.Kind != ASTKindStart {
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stack.MarkComplete(k)
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}
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expr := newExpression(tok)
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stack.Push(expr)
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case StatementPrimeState:
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if tok.Type() != TokenOp {
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stack.MarkComplete(k)
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continue
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}
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if k.Kind != ASTKindExpr {
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return nil, NewParseError(
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fmt.Sprintf("invalid expression: expected Expr type, but found %T type", k),
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)
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}
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k = trimSpaces(k)
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expr := newEqualExpr(k, tok)
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stack.Push(expr)
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case ValueState:
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// ValueState requires the previous state to either be an equal expression
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// or an expression statement.
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switch k.Kind {
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case ASTKindEqualExpr:
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// assigning a value to some key
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k.AppendChild(newExpression(tok))
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stack.Push(newExprStatement(k))
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case ASTKindExpr:
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k.Root.raw = append(k.Root.raw, tok.Raw()...)
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stack.Push(k)
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case ASTKindExprStatement:
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root := k.GetRoot()
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children := root.GetChildren()
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if len(children) == 0 {
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return nil, NewParseError(
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fmt.Sprintf("invalid expression: AST contains no children %s", k.Kind),
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)
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}
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rhs := children[len(children)-1]
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if rhs.Root.ValueType != QuotedStringType {
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rhs.Root.ValueType = StringType
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rhs.Root.raw = append(rhs.Root.raw, tok.Raw()...)
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}
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children[len(children)-1] = rhs
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root.SetChildren(children)
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stack.Push(k)
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}
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case OpenScopeState:
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if !runeCompare(tok.Raw(), openBrace) {
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return nil, NewParseError("expected '['")
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}
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// If OpenScopeState is not at the start, we must mark the previous ast as complete
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//
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// for example: if previous ast was a skip statement;
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// we should mark it as complete before we create a new statement
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if k.Kind != ASTKindStart {
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stack.MarkComplete(k)
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}
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stmt := newStatement()
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stack.Push(stmt)
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case CloseScopeState:
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if !runeCompare(tok.Raw(), closeBrace) {
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return nil, NewParseError("expected ']'")
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}
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k = trimSpaces(k)
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stack.Push(newCompletedSectionStatement(k))
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case SectionState:
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var stmt AST
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switch k.Kind {
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case ASTKindStatement:
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// If there are multiple literals inside of a scope declaration,
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// then the current token's raw value will be appended to the Name.
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//
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// This handles cases like [ profile default ]
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//
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// k will represent a SectionStatement with the children representing
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// the label of the section
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stmt = newSectionStatement(tok)
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case ASTKindSectionStatement:
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k.Root.raw = append(k.Root.raw, tok.Raw()...)
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stmt = k
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default:
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return nil, NewParseError(
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fmt.Sprintf("invalid statement: expected statement: %v", k.Kind),
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)
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}
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stack.Push(stmt)
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case MarkCompleteState:
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if k.Kind != ASTKindStart {
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stack.MarkComplete(k)
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}
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if stack.Len() == 0 {
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stack.Push(start)
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}
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case SkipState:
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stack.Push(newSkipStatement(k))
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s.Skip()
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case CommentState:
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if k.Kind == ASTKindStart {
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stack.Push(k)
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} else {
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stack.MarkComplete(k)
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}
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stmt := newCommentStatement(tok)
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stack.Push(stmt)
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default:
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return nil, NewParseError(
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fmt.Sprintf("invalid state with ASTKind %v and TokenType %v",
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k, tok.Type()))
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}
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if len(tokens) > 0 {
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tokens = tokens[1:]
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}
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}
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// this occurs when a statement has not been completed
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if stack.top > 1 {
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return nil, NewParseError(fmt.Sprintf("incomplete ini expression"))
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}
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// returns a sublist which excludes the start symbol
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return stack.List(), nil
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}
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// trimSpaces will trim spaces on the left and right hand side of
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// the literal.
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func trimSpaces(k AST) AST {
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// trim left hand side of spaces
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for i := 0; i < len(k.Root.raw); i++ {
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if !isWhitespace(k.Root.raw[i]) {
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break
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}
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k.Root.raw = k.Root.raw[1:]
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i--
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}
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// trim right hand side of spaces
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for i := len(k.Root.raw) - 1; i >= 0; i-- {
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if !isWhitespace(k.Root.raw[i]) {
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break
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}
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k.Root.raw = k.Root.raw[:len(k.Root.raw)-1]
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}
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return k
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}
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