mirror of
https://github.com/astaxie/beego.git
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374 lines
5.5 KiB
Go
374 lines
5.5 KiB
Go
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package govaluate
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import (
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"errors"
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"fmt"
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)
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type lexerState struct {
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isEOF bool
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isNullable bool
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kind TokenKind
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validNextKinds []TokenKind
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}
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// lexer states.
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// Constant for all purposes except compiler.
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var validLexerStates = []lexerState{
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lexerState{
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kind: UNKNOWN,
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isEOF: false,
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isNullable: true,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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PATTERN,
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FUNCTION,
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ACCESSOR,
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STRING,
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TIME,
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CLAUSE,
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},
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},
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lexerState{
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kind: CLAUSE,
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isEOF: false,
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isNullable: true,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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PATTERN,
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FUNCTION,
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ACCESSOR,
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STRING,
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TIME,
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CLAUSE,
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CLAUSE_CLOSE,
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},
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},
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lexerState{
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kind: CLAUSE_CLOSE,
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isEOF: true,
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isNullable: true,
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validNextKinds: []TokenKind{
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COMPARATOR,
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MODIFIER,
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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STRING,
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PATTERN,
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TIME,
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CLAUSE,
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CLAUSE_CLOSE,
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LOGICALOP,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: NUMERIC,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: BOOLEAN,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: STRING,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: TIME,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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SEPARATOR,
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},
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},
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lexerState{
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kind: PATTERN,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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SEPARATOR,
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},
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},
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lexerState{
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kind: VARIABLE,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: MODIFIER,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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STRING,
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BOOLEAN,
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CLAUSE,
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CLAUSE_CLOSE,
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},
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},
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lexerState{
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kind: COMPARATOR,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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STRING,
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TIME,
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CLAUSE,
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CLAUSE_CLOSE,
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PATTERN,
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},
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},
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lexerState{
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kind: LOGICALOP,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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STRING,
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TIME,
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CLAUSE,
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CLAUSE_CLOSE,
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},
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},
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lexerState{
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kind: PREFIX,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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NUMERIC,
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BOOLEAN,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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CLAUSE,
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CLAUSE_CLOSE,
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},
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},
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lexerState{
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kind: TERNARY,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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STRING,
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TIME,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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CLAUSE,
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SEPARATOR,
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},
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},
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lexerState{
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kind: FUNCTION,
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isEOF: false,
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isNullable: false,
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validNextKinds: []TokenKind{
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CLAUSE,
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},
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},
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lexerState{
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kind: ACCESSOR,
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isEOF: true,
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isNullable: false,
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validNextKinds: []TokenKind{
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CLAUSE,
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MODIFIER,
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COMPARATOR,
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LOGICALOP,
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CLAUSE_CLOSE,
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TERNARY,
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SEPARATOR,
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},
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},
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lexerState{
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kind: SEPARATOR,
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isEOF: false,
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isNullable: true,
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validNextKinds: []TokenKind{
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PREFIX,
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NUMERIC,
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BOOLEAN,
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STRING,
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TIME,
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VARIABLE,
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FUNCTION,
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ACCESSOR,
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CLAUSE,
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},
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},
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}
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func (this lexerState) canTransitionTo(kind TokenKind) bool {
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for _, validKind := range this.validNextKinds {
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if validKind == kind {
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return true
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}
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}
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return false
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}
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func checkExpressionSyntax(tokens []ExpressionToken) error {
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var state lexerState
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var lastToken ExpressionToken
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var err error
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state = validLexerStates[0]
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for _, token := range tokens {
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if !state.canTransitionTo(token.Kind) {
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// call out a specific error for tokens looking like they want to be functions.
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if lastToken.Kind == VARIABLE && token.Kind == CLAUSE {
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return errors.New("Undefined function " + lastToken.Value.(string))
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}
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firstStateName := fmt.Sprintf("%s [%v]", state.kind.String(), lastToken.Value)
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nextStateName := fmt.Sprintf("%s [%v]", token.Kind.String(), token.Value)
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return errors.New("Cannot transition token types from " + firstStateName + " to " + nextStateName)
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}
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state, err = getLexerStateForToken(token.Kind)
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if err != nil {
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return err
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}
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if !state.isNullable && token.Value == nil {
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errorMsg := fmt.Sprintf("Token kind '%v' cannot have a nil value", token.Kind.String())
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return errors.New(errorMsg)
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}
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lastToken = token
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}
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if !state.isEOF {
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return errors.New("Unexpected end of expression")
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}
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return nil
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}
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func getLexerStateForToken(kind TokenKind) (lexerState, error) {
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for _, possibleState := range validLexerStates {
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if possibleState.kind == kind {
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return possibleState, nil
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}
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}
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errorMsg := fmt.Sprintf("No lexer state found for token kind '%v'\n", kind.String())
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return validLexerStates[0], errors.New(errorMsg)
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}
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