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