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