339 lines
8.6 KiB
Go
339 lines
8.6 KiB
Go
package parser
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import "git.tebibyte.media/arf/arf/lexer"
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// operatorTokens lists all symbolic tokens that can act as a command to a
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// phrase.
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var operatorTokens = []lexer.TokenKind {
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lexer.TokenKindColon,
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lexer.TokenKindPlus,
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lexer.TokenKindMinus,
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lexer.TokenKindIncrement,
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lexer.TokenKindDecrement,
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lexer.TokenKindAsterisk,
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lexer.TokenKindSlash,
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lexer.TokenKindExclamation,
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lexer.TokenKindPercent,
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lexer.TokenKindPercentAssignment,
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lexer.TokenKindTilde,
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lexer.TokenKindTildeAssignment,
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lexer.TokenKindAssignment,
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lexer.TokenKindEqualTo,
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lexer.TokenKindNotEqualTo,
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lexer.TokenKindLessThanEqualTo,
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lexer.TokenKindLessThan,
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lexer.TokenKindLShift,
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lexer.TokenKindLShiftAssignment,
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lexer.TokenKindGreaterThan,
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lexer.TokenKindGreaterThanEqualTo,
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lexer.TokenKindRShift,
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lexer.TokenKindRShiftAssignment,
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lexer.TokenKindBinaryOr,
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lexer.TokenKindBinaryOrAssignment,
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lexer.TokenKindLogicalOr,
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lexer.TokenKindBinaryAnd,
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lexer.TokenKindBinaryAndAssignment,
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lexer.TokenKindLogicalAnd,
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lexer.TokenKindBinaryXor,
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lexer.TokenKindBinaryXorAssignment,
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}
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// isTokenOperator returns whether or not the token is an operator token.
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func isTokenOperator (token lexer.Token) (isOperator bool) {
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for _, kind := range operatorTokens {
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if token.Is(kind) {
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isOperator = true
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return
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}
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}
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return
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}
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// validPhraseStartTokens lists all tokens that are expected when parsing the
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// first part of a phrase.
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var validPhraseStartTokens = append (
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operatorTokens,
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lexer.TokenKindLBracket,
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lexer.TokenKindName,
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lexer.TokenKindString)
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// validBlockLevelPhraseTokens lists all tokens that are expected when parsing
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// a block level phrase.
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var validBlockLevelPhraseTokens = append (
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validArgumentStartTokens,
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lexer.TokenKindNewline,
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lexer.TokenKindReturnDirection)
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// validDelimitedPhraseTokens is like validBlockLevelPhraseTokens, but it also
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// includes a right brace token.
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var validDelimitedPhraseTokens = append (
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validArgumentStartTokens,
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lexer.TokenKindNewline,
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lexer.TokenKindIndent,
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lexer.TokenKindRBracket,
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lexer.TokenKindReturnDirection)
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// controlFlowKinds contains a list of all phrase kinds that must have a block
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// underneath them.
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var controlFlowKinds = []PhraseKind {
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PhraseKindIf,
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PhraseKindElse,
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PhraseKindElseIf,
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PhraseKindFor,
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PhraseKindWhile,
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PhraseKindDefer,
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PhraseKindCase,
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}
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// parseBlock parses an indented block of phrases
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func (parser *parsingOperation) parseBlock (
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indent int,
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) (
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block Block,
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err error,
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) {
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for {
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// if we've left the block, stop parsing
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if !parser.token.Is(lexer.TokenKindIndent) { return }
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if parser.token.Value().(int) != indent { return }
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var phrase Phrase
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phrase, err = parser.parseBlockLevelPhrase(indent)
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block = append(block, phrase)
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if err != nil { return }
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}
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}
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// parseBlockLevelPhrase parses a phrase that is not being used as an argument
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// to something else. This method is allowed to do things like parse return
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// directions, and indented blocks beneath the phrase.
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func (parser *parsingOperation) parseBlockLevelPhrase (
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indent int,
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) (
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phrase Phrase,
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err error,
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) {
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if !parser.token.Is(lexer.TokenKindIndent) { return }
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if parser.token.Value().(int) != indent { return }
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err = parser.nextToken(validPhraseStartTokens...)
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if err != nil { return }
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expectRightBracket := false
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if parser.token.Is(lexer.TokenKindLBracket) {
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expectRightBracket = true
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err = parser.nextToken()
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if err != nil { return }
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}
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// get command
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err = parser.expect(validPhraseStartTokens...)
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if err != nil { return }
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phrase.command,
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phrase.kind,
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phrase.operator,
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err = parser.parsePhraseCommand()
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if err != nil { return }
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for {
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if expectRightBracket {
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// delimited
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// [someFunc arg1 arg2 arg3] -> someVariable
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err = parser.expect(validDelimitedPhraseTokens...)
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if err != nil { return }
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// we are delimited so we can safely skip whitespace
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err = parser.skipWhitespace()
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if err != nil { return }
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if parser.token.Is(lexer.TokenKindRBracket) {
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// this is an ending delimiter
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err = parser.nextToken()
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if err != nil { return }
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break
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}
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} else {
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// not delimited
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// someFunc arg1 arg2 arg3 -> someVariable
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err = parser.expect(validBlockLevelPhraseTokens...)
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if err != nil { return }
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if parser.token.Is(lexer.TokenKindReturnDirection) {
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// we've reached a return direction, so that
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// means this is the end of the phrase
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break
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} else if parser.token.Is(lexer.TokenKindNewline) {
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// we've reached the end of the line, so that
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// means this is the end of the phrase.
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break
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}
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}
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// if we've got this far, we are parsing an argument
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var argument Argument
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argument, err = parser.parseArgument()
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phrase.arguments = append(phrase.arguments, argument)
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}
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// expect newline or return direction
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err = parser.expect (
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lexer.TokenKindNewline,
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lexer.TokenKindReturnDirection)
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if err != nil { return }
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expectReturnDirection := parser.token.Is(lexer.TokenKindReturnDirection)
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// if we have hit a return direction, parse it...
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if expectReturnDirection {
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err = parser.nextToken()
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if err != nil { return }
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for {
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err = parser.expect (
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lexer.TokenKindNewline,
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lexer.TokenKindName)
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if err != nil { return }
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// ...until we hit a newline
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if parser.token.Is(lexer.TokenKindNewline) { break }
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var returnee Argument
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returnee, err = parser.parseArgument()
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if err != nil { return }
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phrase.returnees = append(phrase.returnees, returnee)
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}
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}
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err = parser.nextToken()
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if err != nil { return }
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// if this is a control flow phrase, parse block under it
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isControlFlow := false
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for _, kind := range controlFlowKinds {
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if phrase.kind == kind {
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isControlFlow = true
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break
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}
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}
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if isControlFlow {
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phrase.block, err = parser.parseBlock(indent + 1)
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}
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return
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}
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// parseArgumentLevelPhrase parses a phrase that is being used as an argument to
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// something. It is forbidden from using return direction, and it must be
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// delimited by brackets.
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func (parser *parsingOperation) parseArgumentLevelPhrase () (
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phrase Phrase,
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err error,
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) {
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err = parser.expect(lexer.TokenKindLBracket)
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if err != nil { return }
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// get command
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err = parser.nextToken(validPhraseStartTokens...)
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if err != nil { return }
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phrase.command,
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phrase.kind,
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phrase.operator,
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err = parser.parsePhraseCommand()
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if err != nil { return }
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for {
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// delimited
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// [someFunc arg1 arg2 arg3] -> someVariable
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err = parser.expect(validDelimitedPhraseTokens...)
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if err != nil { return }
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if parser.token.Is(lexer.TokenKindRBracket) {
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// this is an ending delimiter
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err = parser.nextToken()
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if err != nil { return }
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return
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} else if parser.token.Is(lexer.TokenKindNewline) {
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// we are delimited, so we can safely skip
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// newlines
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err = parser.nextToken()
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if err != nil { return }
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continue
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} else if parser.token.Is(lexer.TokenKindIndent) {
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// we are delimited, so we can safely skip
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// indents
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err = parser.nextToken()
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if err != nil { return }
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continue
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}
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// this is an argument
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var argument Argument
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argument, err = parser.parseArgument()
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phrase.arguments = append(phrase.arguments, argument)
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}
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}
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// parsePhraseCommand parses the command argument of a phrase.
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func (parser *parsingOperation) parsePhraseCommand () (
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command Argument,
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kind PhraseKind,
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operator lexer.TokenKind,
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err error,
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) {
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if isTokenOperator(parser.token) {
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err = parser.expect(operatorTokens...)
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if err != nil { return }
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if parser.token.Is(lexer.TokenKindColon) {
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kind = PhraseKindCase
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} else if parser.token.Is(lexer.TokenKindAssignment) {
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kind = PhraseKindAssign
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} else {
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kind = PhraseKindOperator
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operator = parser.token.Kind()
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}
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err = parser.nextToken()
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return
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}
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// phrase command is not an operator, it is just a normal argument
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command, err = parser.parseArgument()
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if err != nil { return }
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// determine semantic role of phrase
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if command.kind == ArgumentKindString {
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kind = PhraseKindArbitrary
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} else if command.kind == ArgumentKindIdentifier {
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identifier := command.value.(Identifier)
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if len(identifier.trail) == 1 {
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switch identifier.trail[0] {
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case "loc":
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kind = PhraseKindReference
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case "cast":
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kind = PhraseKindCast
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case "defer":
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kind = PhraseKindDefer
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case "if":
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kind = PhraseKindIf
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case "elseif":
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kind = PhraseKindElseIf
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case "else":
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kind = PhraseKindElse
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case "switch":
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kind = PhraseKindSwitch
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case "while":
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kind = PhraseKindWhile
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case "for":
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kind = PhraseKindFor
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}
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}
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}
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return
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}
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