Clinical Quality Language Release 1 STU 3 (1.3)

This is the current officially released version of Clinical Quality Language, 1.3.
For a full list of available versions, see the Directory of published versions .

Clinical Decision Support Work GroupMaturity Level: 4Ballot Status: STU 3

Clinical Quality Language Grammar

This page contains the Antlr 4.0 grammar for Clinical Quality Language.

Raw CQL grammar

grammar cql;

/*
 * Clinical Quality Language Grammar Specification
 * Version 1.3 - STU3 Publication
 */

import fhirpath;

/*
 * Parser Rules
 */

library
    :
    libraryDefinition?
    usingDefinition*
    includeDefinition*
    codesystemDefinition*
    valuesetDefinition*
    codeDefinition*
    conceptDefinition*
    parameterDefinition*
    statement*
    ;

/*
 * Definitions
 */

libraryDefinition
    : 'library' identifier ('version' versionSpecifier)?
    ;

usingDefinition
    : 'using' modelIdentifier ('version' versionSpecifier)?
    ;

includeDefinition
    : 'include' identifier ('version' versionSpecifier)? ('called' localIdentifier)?
    ;

localIdentifier
    : identifier
    ;

accessModifier
    : 'public'
    | 'private'
    ;

parameterDefinition
    : accessModifier? 'parameter' identifier (typeSpecifier)? ('default' expression)?
    ;

codesystemDefinition
    : accessModifier? 'codesystem' identifier ':' codesystemId ('version' versionSpecifier)?
    ;

valuesetDefinition
    : accessModifier? 'valueset' identifier ':' valuesetId ('version' versionSpecifier)? codesystems?
    ;

codesystems
    : 'codesystems' '{' codesystemIdentifier (',' codesystemIdentifier)* '}'
    ;

codesystemIdentifier
    : (libraryIdentifier '.')? identifier
    ;

libraryIdentifier
    : identifier
    ;

codeDefinition
    : accessModifier? 'code' identifier ':' codeId 'from' codesystemIdentifier displayClause?
    ;

conceptDefinition
    : accessModifier? 'concept' identifier ':' '{' codeIdentifier (',' codeIdentifier)* '}' displayClause?
    ;

codeIdentifier
    : (libraryIdentifier '.')? identifier
    ;

codesystemId
    : STRING
    ;

valuesetId
    : STRING
    ;

versionSpecifier
    : STRING
    ;

codeId
    : STRING
    ;

/*
 * Type Specifiers
 */

typeSpecifier
    : namedTypeSpecifier
    | listTypeSpecifier
    | intervalTypeSpecifier
    | tupleTypeSpecifier
    | choiceTypeSpecifier
    ;

namedTypeSpecifier
    : (qualifier '.')* identifier
    ;

modelIdentifier
    : identifier
    ;

listTypeSpecifier
    : 'List' '<' typeSpecifier '>'
    ;

intervalTypeSpecifier
    : 'Interval' '<' typeSpecifier '>'
    ;

tupleTypeSpecifier
    : 'Tuple' '{' tupleElementDefinition (',' tupleElementDefinition)* '}'
    ;

tupleElementDefinition
    : identifier typeSpecifier
    ;

choiceTypeSpecifier
    : 'Choice' '<' typeSpecifier (',' typeSpecifier)* '>'
    ;

/*
 * Statements
 */

statement
    : expressionDefinition
    | contextDefinition
    | functionDefinition
    ;

expressionDefinition
    : 'define' accessModifier? identifier ':' expression
    ;

contextDefinition
    : 'context' identifier
    ;

functionDefinition
    : 'define' accessModifier? 'function' identifier '(' (operandDefinition (',' operandDefinition)*)? ')'
        ('returns' typeSpecifier)?
        ':' (functionBody | 'external')
    ;

operandDefinition
    : identifier typeSpecifier
    ;

functionBody
    : expression
    ;

/*
 * Expressions
 */

querySource
    : retrieve
    | qualifiedIdentifier
    | '(' expression ')'
    ;

aliasedQuerySource
    : querySource alias
    ;

alias
    : identifier
    ;

queryInclusionClause
    : withClause
    | withoutClause
    ;

withClause
    : 'with' aliasedQuerySource 'such that' expression
    ;

withoutClause
    : 'without' aliasedQuerySource 'such that' expression
    ;

retrieve
    : '[' namedTypeSpecifier (':' (codePath 'in')? terminology)? ']'
    ;

codePath
    : identifier
    ;

terminology
    : qualifiedIdentifier
    | expression
    ;

qualifier
    : identifier
    ;

query
    : sourceClause letClause? queryInclusionClause* whereClause? returnClause? sortClause?
    ;

sourceClause
    : 'from'? aliasedQuerySource (',' aliasedQuerySource)*
    ;

letClause
    : 'let' letClauseItem (',' letClauseItem)*
    ;

letClauseItem
    : identifier ':' expression
    ;

whereClause
    : 'where' expression
    ;

returnClause
    : 'return' ('all' | 'distinct')? expression
    ;

sortClause
    : 'sort' ( sortDirection | ('by' sortByItem (',' sortByItem)*) )
    ;

sortDirection
    : 'asc' | 'ascending'
    | 'desc' | 'descending'
    ;

sortByItem
    : expressionTerm sortDirection?
    ;

qualifiedIdentifier
    : (qualifier '.')* identifier
    ;

expression
    : expressionTerm                                                                                #termExpression
    | retrieve                                                                                      #retrieveExpression
    | query                                                                                         #queryExpression
    | expression 'is' 'not'? ('null' | 'true' | 'false')                                            #booleanExpression
    | expression ('is' | 'as') typeSpecifier                                                        #typeExpression
    | 'cast' expression 'as' typeSpecifier                                                          #castExpression
    | 'not' expression                                                                              #notExpression
    | 'exists' expression                                                                           #existenceExpression
    | expression 'properly'? 'between' expressionTerm 'and' expressionTerm                          #betweenExpression
    | ('duration' 'in')? pluralDateTimePrecision 'between' expressionTerm 'and' expressionTerm      #durationBetweenExpression
    | 'difference' 'in' pluralDateTimePrecision 'between' expressionTerm 'and' expressionTerm       #differenceBetweenExpression
    | expression ('<=' | '<' | '>' | '>=') expression                                               #inequalityExpression
    | expression intervalOperatorPhrase expression                                                  #timingExpression
    | expression ('=' | '!=' | '~' | '!~') expression                                               #equalityExpression
    | expression ('in' | 'contains') dateTimePrecisionSpecifier? expression                         #membershipExpression
    | expression 'and' expression                                                                   #andExpression
    | expression ('or' | 'xor') expression                                                          #orExpression
    | expression 'implies' expression                                                               #impliesExpression
    | expression ('|' | 'union' | 'intersect' | 'except') expression                                #inFixSetExpression
    ;

dateTimePrecision
    : 'year' | 'month' | 'week' | 'day' | 'hour' | 'minute' | 'second' | 'millisecond'
    ;

dateTimeComponent
    : dateTimePrecision
    | 'date'
    | 'time'
    | 'timezone'
    ;

pluralDateTimePrecision
    : 'years' | 'months' | 'weeks' | 'days' | 'hours' | 'minutes' | 'seconds' | 'milliseconds'
    ;

expressionTerm
    : term                                                                          #termExpressionTerm
    | expressionTerm '.' invocation                                                 #invocationExpressionTerm
    | expressionTerm '[' expression ']'                                             #indexedExpressionTerm
    | 'convert' expression 'to' typeSpecifier                                       #conversionExpressionTerm
    | ('+' | '-') expressionTerm                                                    #polarityExpressionTerm
    | ('start' | 'end') 'of' expressionTerm                                         #timeBoundaryExpressionTerm
    | dateTimeComponent 'from' expressionTerm                                       #timeUnitExpressionTerm
    | 'duration' 'in' pluralDateTimePrecision 'of' expressionTerm                   #durationExpressionTerm
    | 'difference' 'in' pluralDateTimePrecision 'of' expressionTerm                 #differenceExpressionTerm
    | 'width' 'of' expressionTerm                                                   #widthExpressionTerm
    | 'successor' 'of' expressionTerm                                               #successorExpressionTerm
    | 'predecessor' 'of' expressionTerm                                             #predecessorExpressionTerm
    | 'singleton' 'from' expressionTerm                                             #elementExtractorExpressionTerm
    | 'point' 'from' expressionTerm                                                 #pointExtractorExpressionTerm
    | ('minimum' | 'maximum') namedTypeSpecifier                                    #typeExtentExpressionTerm
    | expressionTerm '^' expressionTerm                                             #powerExpressionTerm
    | expressionTerm ('*' | '/' | 'div' | 'mod') expressionTerm                     #multiplicationExpressionTerm
    | expressionTerm ('+' | '-' | '&') expressionTerm                               #additionExpressionTerm
    | 'if' expression 'then' expression 'else' expression                           #ifThenElseExpressionTerm
    | 'case' expression? caseExpressionItem+ 'else' expression 'end'                #caseExpressionTerm
    | ('distinct' | 'flatten') expression                                           #aggregateExpressionTerm
    | ('expand' | 'collapse') expression ('per' (dateTimePrecision | expression))?  #setAggregateExpressionTerm
    ;

caseExpressionItem
    : 'when' expression 'then' expression
    ;

dateTimePrecisionSpecifier
    : dateTimePrecision 'of'
    ;

relativeQualifier
    : 'or before'
    | 'or after'
    ;

offsetRelativeQualifier
    : 'or more'
    | 'or less'
    ;

exclusiveRelativeQualifier
    : 'less than'
    | 'more than'
    ;

quantityOffset
    : (quantity offsetRelativeQualifier?)
    | (exclusiveRelativeQualifier quantity)
    ;

temporalRelationship
    : ('on or'? ('before' | 'after'))
    | (('before' | 'after') 'or on'?)
    ;

intervalOperatorPhrase
    : ('starts' | 'ends' | 'occurs')? 'same' dateTimePrecision? (relativeQualifier | 'as') ('start' | 'end')?               #concurrentWithIntervalOperatorPhrase
    | 'properly'? 'includes' dateTimePrecisionSpecifier? ('start' | 'end')?                                                 #includesIntervalOperatorPhrase
    | ('starts' | 'ends' | 'occurs')? 'properly'? ('during' | 'included in') dateTimePrecisionSpecifier?                    #includedInIntervalOperatorPhrase
    | ('starts' | 'ends' | 'occurs')? quantityOffset? temporalRelationship dateTimePrecisionSpecifier? ('start' | 'end')?   #beforeOrAfterIntervalOperatorPhrase
    | ('starts' | 'ends' | 'occurs')? 'properly'? 'within' quantity 'of' ('start' | 'end')?                                 #withinIntervalOperatorPhrase
    | 'meets' ('before' | 'after')? dateTimePrecisionSpecifier?                                                             #meetsIntervalOperatorPhrase
    | 'overlaps' ('before' | 'after')? dateTimePrecisionSpecifier?                                                          #overlapsIntervalOperatorPhrase
    | 'starts' dateTimePrecisionSpecifier?                                                                                  #startsIntervalOperatorPhrase
    | 'ends' dateTimePrecisionSpecifier?                                                                                    #endsIntervalOperatorPhrase
    ;

term
    : invocation            #invocationTerm
    | literal               #literalTerm
    | externalConstant      #externalConstantTerm
    | intervalSelector      #intervalSelectorTerm
    | tupleSelector         #tupleSelectorTerm
    | instanceSelector      #instanceSelectorTerm
    | listSelector          #listSelectorTerm
    | codeSelector          #codeSelectorTerm
    | conceptSelector       #conceptSelectorTerm
    | '(' expression ')'    #parenthesizedTerm
    ;

ratio
    : quantity ':' quantity
    ;

literal
        : ('true' | 'false')                                    #booleanLiteral
        | 'null'                                                #nullLiteral
        | STRING                                                #stringLiteral
        | NUMBER                                                #numberLiteral
        | DATETIME                                              #dateTimeLiteral
        | TIME                                                  #timeLiteral
        | quantity                                              #quantityLiteral
        | ratio                                                 #ratioLiteral
        ;

intervalSelector
    : // TODO: Consider this as an alternative syntax for intervals... (would need to be moved up to expression to make it work)
    //expression ( '..' | '*.' | '.*' | '**' ) expression;
    'Interval' ('['|'(') expression ',' expression (']'|')')
    ;

tupleSelector
    : 'Tuple'? '{' (':' | (tupleElementSelector (',' tupleElementSelector)*)) '}'
    ;

tupleElementSelector
    : identifier ':' expression
    ;

instanceSelector
    : namedTypeSpecifier '{' (':' | (instanceElementSelector (',' instanceElementSelector)*)) '}'
    ;

instanceElementSelector
    : identifier ':' expression
    ;

listSelector
    : ('List' ('<' typeSpecifier '>')?)? '{' (expression (',' expression)*)? '}'
    ;

displayClause
    : 'display' STRING
    ;

codeSelector
    : 'Code' STRING 'from' codesystemIdentifier displayClause?
    ;

conceptSelector
    : 'Concept' '{' codeSelector (',' codeSelector)* '}' displayClause?
    ;

identifier
    : IDENTIFIER
    | DELIMITEDIDENTIFIER
    | QUOTEDIDENTIFIER
    | 'all'
    | 'Code'
    | 'code'
    | 'Concept'
    | 'concept'
    | 'contains'
    | 'date'
    | 'display'
    | 'distinct'
    | 'end'
    // | 'exists' NOTE: This is excluded because including it causes a significant performance degradation in the ANTLR parser, still looking into a fix for this
    | 'not'
    | 'start'
    | 'time'
    | 'timezone'
    | 'version'
    | 'where'
    ;

QUOTEDIDENTIFIER
        : '"' (ESC | .)*? '"'
        ;

fragment ESC
        : '\\' ([`'"\\/fnrt] | UNICODE)    // allow \`, \', \", \\, \/, \f, etc. and \uXXX
        ;



NOTE: CQL extends from the FHIRPath grammar, and so uses the core production rules defined there. The FHIRPath grammar is included here for reference only, the FHIRPath grammar below is part of the FHIRPath specification. —-

Raw FHIRPath grammar

grammar fhirpath;

// Grammar rules

//prog: line (line)*;
//line: ID ( '(' expr ')') ':' expr '\r'? '\n';

expression
        : term                                                      #termExpression
        | expression '.' invocation                                 #invocationExpression
        | expression '[' expression ']'                             #indexerExpression
        | ('+' | '-') expression                                    #polarityExpression
        | expression ('*' | '/' | 'div' | 'mod') expression         #multiplicativeExpression
        | expression ('+' | '-' | '&') expression                   #additiveExpression
        | expression ('is' | 'as') typeSpecifier                    #typeExpression
        | expression '|' expression                                 #unionExpression
        | expression ('<=' | '<' | '>' | '>=') expression           #inequalityExpression
        | expression ('=' | '~' | '!=' | '!~') expression           #equalityExpression
        | expression ('in' | 'contains') expression                 #membershipExpression
        | expression 'and' expression                               #andExpression
        | expression ('or' | 'xor') expression                      #orExpression
        | expression 'implies' expression                           #impliesExpression
        //| (IDENTIFIER)? '=>' expression                             #lambdaExpression
        ;

term
        : invocation                                            #invocationTerm
        | literal                                               #literalTerm
        | externalConstant                                      #externalConstantTerm
        | '(' expression ')'                                    #parenthesizedTerm
        ;

literal
        : '{' '}'                                               #nullLiteral
        | ('true' | 'false')                                    #booleanLiteral
        | STRING                                                #stringLiteral
        | NUMBER                                                #numberLiteral
        | DATETIME                                              #dateTimeLiteral
        | TIME                                                  #timeLiteral
        | quantity                                              #quantityLiteral
        ;

externalConstant
        : '%' identifier
        ;

invocation                          // Terms that can be used after the function/member invocation '.'
        : identifier                                            #memberInvocation
        | function                                              #functionInvocation
        | '$this'                                               #thisInvocation
        | '$index'                                              #indexInvocation
        | '$total'                                              #totalInvocation
        ;

function
        : identifier '(' paramList? ')'
        ;

paramList
        : expression (',' expression)*
        ;

quantity
        : NUMBER unit?
        ;

unit
        : dateTimePrecision
        | pluralDateTimePrecision
        | STRING // UCUM syntax for units of measure
        ;

dateTimePrecision
        : 'year' | 'month' | 'week' | 'day' | 'hour' | 'minute' | 'second' | 'millisecond'
        ;

pluralDateTimePrecision
        : 'years' | 'months' | 'weeks' | 'days' | 'hours' | 'minutes' | 'seconds' | 'milliseconds'
        ;

typeSpecifier
        : qualifiedIdentifier
        ;

qualifiedIdentifier
        : identifier ('.' identifier)*
        ;

identifier
        : IDENTIFIER
        | DELIMITEDIDENTIFIER
        | 'as'
        | 'is'
        ;


/****************************************************************
    Lexical rules
*****************************************************************/

// Not sure why, but with these as lexical rules, when the grammar is imported into CQL, they are not correctly recognized
// Moving the same rules into the literal production rule above corrects the issue
//EMPTY
//        : '{' '}'
//        ;                      // To create an empty array (and avoid a NULL literal)

//BOOL
//        : 'true'
//        | 'false'
//        ;

DATETIME
        : '@'
            [0-9][0-9][0-9][0-9] // year
            (
                '-'[0-9][0-9] // month
                (
                    '-'[0-9][0-9] // day
                    (
                        'T' TIMEFORMAT
                    )?
                 )?
             )?
             'Z'? // UTC specifier
        ;

TIME
        : '@' 'T' TIMEFORMAT
        ;

fragment TIMEFORMAT
        :
            [0-9][0-9] (':'[0-9][0-9] (':'[0-9][0-9] ('.'[0-9]+)?)?)?
            ('Z' | ('+' | '-') [0-9][0-9]':'[0-9][0-9])? // timezone
        ;

IDENTIFIER
        : ([A-Za-z] | '_')([A-Za-z0-9] | '_')*            // Added _ to support CQL (FHIR could constrain it out)
        ;

DELIMITEDIDENTIFIER
        : '`' (ESC | .)*? '`'
        ;

STRING
        : '\'' (ESC | .)*? '\''
        ;

// Also allows leading zeroes now (just like CQL and XSD)
NUMBER
        : [0-9]+('.' [0-9]+)?
        ;

// Pipe whitespace to the HIDDEN channel to support retrieving source text through the parser.
WS
        : [ \r\n\t]+ -> channel(HIDDEN)
        ;

COMMENT
        : '/*' .*? '*/' -> channel(HIDDEN)
        ;

LINE_COMMENT
        : '//' ~[\r\n]* -> channel(HIDDEN)
        ;

fragment ESC
        : '\\' ([`'\\/fnrt] | UNICODE)    // allow \`, \', \\, \/, \f, etc. and \uXXX
        ;

fragment UNICODE
        : 'u' HEX HEX HEX HEX
        ;

fragment HEX
        : [0-9a-fA-F]
        ;