Module: FHIRPath
- Defined in:
- lib/fhir_models/fhirpath/parse.rb,
lib/fhir_models/fhirpath/evaluate.rb,
lib/fhir_models/fhirpath/expression.rb
Defined Under Namespace
Classes: Expression
Constant Summary collapse
- @@reserved =
['all', 'not', 'empty', 'exists', 'where', 'select', 'extension', 'startsWith', 'contains', 'in', 'distinct', '=', '!=', '<=', '>=', '<', '>', 'and', 'or', 'xor', '+', '-', '/', '*', 'toInteger', 'implies', 'children', 'first', 'last', 'tail', 'count', 'length', 'substring']
- @@context =
{}
- @@parent =
nil
Class Method Summary collapse
-
.atom(token) ⇒ Object
This method converts a token within an expression to a native number (if applicable) otherwise it considers it to be a symbol.
-
.build_tree(tokens) ⇒ Object
This method builds an Abstract Syntax Tree (AST) from a flat list of tokens.
- .clean_index(tree, index) ⇒ Object
-
.compute(tree, data) ⇒ Object
evaluate a parsed expression given some context data.
-
.convert_to_boolean(value) ⇒ Object
Convert nils and empty Arrays to false Everything else is true.
-
.evaluate(expression, hash, parent = nil) ⇒ Object
This is the entry point to using the FHIRPath class.
-
.get(key, hash) ⇒ Object
Get a value from a hash, with some special handling of self references.
- .parse(expression) ⇒ Object
- .reassemble_strings(tokens) ⇒ Object
-
.tokenize(expression) ⇒ Object
This method tokenizes the expression into a flat array of tokens.
Class Method Details
.atom(token) ⇒ Object
This method converts a token within an expression to a native number (if applicable) otherwise it considers it to be a symbol.
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# File 'lib/fhir_models/fhirpath/parse.rb', line 89 def self.atom(token) # check if it is a number value = token begin value = Float(token) rescue value = token value = token.to_sym if @@reserved.include?(token) value = true if token == 'true' value = false if token == 'false' end value end |
.build_tree(tokens) ⇒ Object
This method builds an Abstract Syntax Tree (AST) from a flat list of tokens
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# File 'lib/fhir_models/fhirpath/parse.rb', line 64 def self.build_tree(tokens) return if tokens.empty? tree = [] until tokens.empty? token = tokens.delete_at(0) if '(' == token # sub expression tree << FHIRPath::Expression.new(build_tree(tokens)) elsif ')' == token return tree elsif '.' != token tree << atom(token) end end # post-processing tree.each_with_index do |t, index| if t == :extension # 'extension' can be a path or a function call (if followed by a block) next_token = tree[index + 1] tree[index] = 'extension' if next_token.nil? || !next_token.is_a?(FHIRPath::Expression) end end tree end |
.clean_index(tree, index) ⇒ Object
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# File 'lib/fhir_models/fhirpath/evaluate.rb', line 65 def self.clean_index(tree, index) tree[index] = nil unless index.nil? end |
.compute(tree, data) ⇒ Object
evaluate a parsed expression given some context data
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# File 'lib/fhir_models/fhirpath/evaluate.rb', line 70 def self.compute(tree, data) tree = tree.tree if tree.is_a?(FHIRPath::Expression) # --------------- OPERATOR PRECEDENCE ------------------ # 01 . (path/function invocation) # 02 [] (indexer) # 03 unary + and - # 04: *, /, div, mod # 05: +, -, # 06: | # 07: >, <, >=, <= # 08: is, as # 09: =, ~, !=, !~ # 10: in, contains # 11: and # 12: xor, or # 13: implies # evaluate all the data at this level functions = [:where, :select, :extension, :children, :first, :last, :tail] size = -1 substitutions = 1 while tree.length != size || substitutions > 0 substitutions = 0 FHIR.logger.debug "DATA: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(String) && !(node.start_with?("'") && node.end_with?("'")) array_index = nil if node.include?('[') && node.end_with?(']') array_index = node[node.index('[')..-1].gsub(/\[|\]/, '') t = get(array_index, data) t = array_index.to_i if t.nil? || t == :null array_index = t node = node[0..node.index('[') - 1] end if previous_node.is_a?(Hash) || previous_node.is_a?(Array) tree[index] = get(node, previous_node) clean_index(tree, previous_index) elsif !previous_node.is_a?(FHIRPath::Expression) tree[index] = get(node, data) end if array_index && tree[index].is_a?(Array) tree[index] = tree[index][array_index] end FHIR.logger.debug "V===> #{tree}" elsif node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) case node when :where # the previous node should be data (as Array or Hash) # the next node should be a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'Where function requires a block.' end previous_node = [] if previous_node == :null if previous_node.is_a?(Array) previous_node.keep_if do |item| sub = compute(block.clone, item) convert_to_boolean(sub) end tree[index] = previous_node clean_index(tree, previous_index) elsif previous_node.is_a?(Hash) sub = compute(block, previous_node) tree[index] = convert_to_boolean(sub) ? previous_node : {} clean_index(tree, previous_index) else raise "Where function not applicable to #{previous_node.class}: #{previous_node}" end break when :select # select is equivalent to ruby Array.map! # the previous node should be data (as Array or Hash) # the next node should be a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'Select function requires a block.' end previous_node = [] if previous_node == :null if previous_node.is_a?(Array) previous_node.map! do |item| compute(block.clone, item) end tree[index] = previous_node clean_index(tree, previous_index) elsif previous_node.is_a?(Hash) tree[index] = compute(block, previous_node) clean_index(tree, previous_index) else raise "Select function not applicable to #{previous_node.class}: #{previous_node}" end break when :extension # the previous node should be a data (as Hash) # the next node optionally is a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'Extension function requires a block.' end if previous_node.is_a?(Hash) FHIR.logger.debug 'Evaling Extension Block....' exts = data['extension'] if exts.is_a?(Array) url = nil begin url = block.tree.first.gsub(/\'|\"/, '') rescue raise 'Extension function requires a single URL as String.' end ext = exts.select { |x| x['url'] == url }.first tree[index] = ext clean_index(tree, previous_index) else raise "Extension function not applicable to #{exts.class}: #{exts}" end else raise "Extension not applicable to #{previous_node.class}: #{previous_node}" end break when :children # if there is a previous node, it should be data (as Hash) # otherwise, use the context as data if previous_node.is_a?(Hash) tree[index] = previous_node.values clean_index(tree, previous_index) substitutions += 1 elsif data.is_a?(Hash) tree[index] = data.values substitutions += 1 else raise "Children not applicable to #{previous_node.class}: #{previous_node}" end break when :first # the previous node should be an Array of length > 1 if previous_node.is_a?(Array) tree[index] = previous_node.first clean_index(tree, previous_index) else raise "First function is not applicable to #{previous_node.class}: #{previous_node}" end when :last # the previous node should be an Array of length > 1 if previous_node.is_a?(Array) tree[index] = previous_node.last clean_index(tree, previous_index) else raise "Last function is not applicable to #{previous_node.class}: #{previous_node}" end when :tail # the previous node should be an Array of length > 1 if previous_node.is_a?(Array) tree[index] = previous_node.last(previous_node.length - 1) clean_index(tree, previous_index) else raise "Tail function is not applicable to #{previous_node.class}: #{previous_node}" end end FHIR.logger.debug "F===> #{tree}" end previous_index = index previous_node = tree[index] end FHIR.logger.debug '---------------------------------------------------' tree.compact! end tree.each_with_index do |node, index| tree[index] = node[1..-2] if node.is_a?(String) && node.start_with?("'") && node.end_with?("'") end FHIR.logger.debug "DATA: #{tree}" # evaluate all the functions at this level functions = [:all, :not, :empty, :exists, :startsWith, :substring, :contains, :in, :distinct, :toInteger, :count, :length] size = -1 while tree.length != size FHIR.logger.debug "FUNC: #{tree}" previous_node = data previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) case node when :all if previous_node.is_a?(Array) result = true previous_node.each { |item| result = (result && convert_to_boolean(item)) } tree[index] = result else tree[index] = convert_to_boolean(previous_node) end clean_index(tree, previous_index) when :not tree[index] = !convert_to_boolean(previous_node) clean_index(tree, previous_index) when :count tree[index] = 0 tree[index] = 1 unless previous_node == :null || previous_node.nil? tree[index] = previous_node.length if previous_node.is_a?(Array) clean_index(tree, previous_index) when :length if previous_node == :null || previous_node.nil? tree[index] = 0 else tree[index] = previous_node.to_s.length end clean_index(tree, previous_index) when :empty tree[index] = (previous_node == :null || previous_node.empty? rescue previous_node.nil?) clean_index(tree, previous_index) when :exists tree[index] = !previous_node.nil? && previous_node != :null && previous_node != [] clean_index(tree, previous_index) when :distinct tree[index] = (previous_node.uniq rescue previous_node) clean_index(tree, previous_index) when :startsWith # the previous node should be a data (as String) # the next node should be a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'StartsWith function requires a block.' end if previous_node.is_a?(String) FHIR.logger.debug 'Evaling StartsWith Block....' prefix = compute(block, data) tree[index] = previous_node.start_with?(prefix) rescue false clean_index(tree, previous_index) else raise "StartsWith function not applicable to #{previous_node.class}: #{previous_node}" end break when :substring # the previous node should be a data (as String) # the next node should be a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'Substring function requires a block.' end if previous_node.is_a?(String) args = block.tree.first start = 0 length = previous_node.length if args.is_a?(String) && args.include?(',') args = args.split(',') start = args.first.to_i length = args.last.to_i - 1 else FHIR.logger.debug 'Evaling Substring Block....' start = compute(block, data) length = previous_node.length - start end tree[index] = previous_node[start..(start + length)] clean_index(tree, previous_index) else raise "Substring function not applicable to #{previous_node.class}: #{previous_node}" end break when :contains # the previous node should be a data (as String) # the next node should be a block or subexpression (as FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) tree[index + 1] = nil else raise 'Contains function requires a block.' end if previous_node.is_a?(String) FHIR.logger.debug 'Evaling Contains Block....' substring = compute(block, data) tree[index] = previous_node.include?(substring) rescue false clean_index(tree, previous_index) else raise "Contains function not applicable to #{previous_node.class}: #{previous_node}" end break when :in # the previous node should be a data (as String, Number, or Boolean) # the next node should an Array (possibly as a block or subexpression/FHIRPath::Expression) block = tree[index + 1] if block.is_a?(FHIRPath::Expression) FHIR.logger.debug 'Evaling In Block....' tree[index + 1] = compute(block, data) end array = tree[index + 1] if array.is_a?(Array) tree[index + 1] = nil else raise 'In function requires an array.' end if previous_node.is_a?(String) || previous_node == true || previous_node == false || previous_node.is_a?(Numeric) tree[index] = array.include?(previous_node) rescue false clean_index(tree, previous_index) else raise "In function not applicable to #{previous_node.class}: #{previous_node}" end break when :toInteger # the previous node should be a data (as String, Integer, Boolean) if previous_node.is_a?(String) tree[index] = previous_node.to_i rescue 0 elsif previous_node.is_a?(Numeric) tree[index] = previous_node.to_i else tree[index] = 0 tree[index] = 1 if convert_to_boolean(previous_node) end clean_index(tree, previous_index) break else raise "Function not implemented: #{node}" end end previous_index = index previous_node = node end tree.compact! end # evaluate all mult/div functions = [:"/", :"*"] size = -1 while tree.length != size FHIR.logger.debug "MATH: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) tree[index + 1] = compute(tree[index + 1], data) if tree[index + 1].is_a?(FHIRPath::Expression) left = previous_node right = tree[index + 1] case node when :"/" tree[index] = (left / right) when :"*" tree[index] = (left * right) end tree[previous_index] = nil tree[index + 1] = nil break end previous_index = index previous_node = node end tree.compact! end FHIR.logger.debug "MATH: #{tree}" # evaluate all add/sub functions = [:"+", :"-"] size = -1 while tree.length != size FHIR.logger.debug "MATH: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) tree[index + 1] = compute(tree[index + 1], data) if tree[index + 1].is_a?(FHIRPath::Expression) left = previous_node right = tree[index + 1] case node when :"+" tree[index] = (left + right) when :"-" tree[index] = (left - right) end tree[previous_index] = nil tree[index + 1] = nil break end previous_index = index previous_node = node end tree.compact! end FHIR.logger.debug "MATH: #{tree}" # evaluate all equality tests functions = [:"=", :"!=", :"<=", :">=", :"<", :">"] size = -1 while tree.length != size FHIR.logger.debug "EQ: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) tree[index + 1] = compute(tree[index + 1], data) if tree[index + 1].is_a?(FHIRPath::Expression) left = previous_node right = tree[index + 1] case node when :"=" tree[index] = (left == right) when :"!=" tree[index] = (left != right) when :"<=" tree[index] = (left <= right) when :">=" tree[index] = (left >= right) when :"<" tree[index] = (left < right) when :">" tree[index] = (left > right) else raise "Equality operator not implemented: #{node}" end tree[previous_index] = nil tree[index + 1] = nil break end previous_index = index previous_node = node end tree.compact! end FHIR.logger.debug "EQ: #{tree}" # evaluate all logical tests functions = [:and, :or, :xor] size = -1 while tree.length != size FHIR.logger.debug "LOGIC: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) tree[index + 1] = compute(tree[index + 1], data) if tree[index + 1].is_a?(FHIRPath::Expression) left = convert_to_boolean(previous_node) right = convert_to_boolean(tree[index + 1]) case node when :and tree[index] = (left && right) when :or tree[index] = (left || right) when :xor tree[index] = (left ^ right) else raise "Logical operator not implemented: #{node}" end tree[previous_index] = nil tree[index + 1] = nil break end previous_index = index previous_node = node end tree.compact! end FHIR.logger.debug "LOGIC: #{tree}" functions = [:implies] size = -1 while tree.length != size FHIR.logger.debug "IMPLIES: #{tree}" previous_node = nil previous_index = nil size = tree.length tree.each_with_index do |node, index| if node.is_a?(Symbol) && functions.include?(node) previous_node = compute(previous_node, data) if previous_node.is_a?(FHIRPath::Expression) tree[index + 1] = compute(tree[index + 1], data) if tree[index + 1].is_a?(FHIRPath::Expression) case node when :implies tree[index] = false exists = !previous_node.nil? && previous_node != :null implication = convert_to_boolean(tree[index + 1]) tree[index] = true if exists && (implication || tree[index + 1] == false) else raise "Logical operator not implemented: #{node}" end tree[previous_index] = nil tree[index + 1] = nil break end previous_index = index previous_node = node end tree.compact! end FHIR.logger.debug "IMPLIES: #{tree}" # check for symbols tree.each do |node| raise "Unhandled reserved symbol: #{node}" if node.is_a?(Symbol) end FHIR.logger.debug "OUT: #{tree}" tree.map! do |out| while out.is_a?(FHIRPath::Expression) out = compute(out, data) end out end FHIR.logger.debug "RETURN: #{tree.first}" tree.first end |
.convert_to_boolean(value) ⇒ Object
Convert nils and empty Arrays to false Everything else is true.
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# File 'lib/fhir_models/fhirpath/evaluate.rb', line 56 def self.convert_to_boolean(value) return false if value.nil? return false if value.is_a?(Array) && value.empty? return false if value.is_a?(Hash) && value.empty? return false if value == :null return false if value == false true end |
.evaluate(expression, hash, parent = nil) ⇒ Object
This is the entry point to using the FHIRPath class
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# File 'lib/fhir_models/fhirpath/evaluate.rb', line 6 def self.evaluate(expression, hash, parent = nil) @@context = hash @@parent = parent tree = FHIRPath.parse(expression) FHIR.logger.debug "TREE: #{tree}" compute(tree, hash) end |
.get(key, hash) ⇒ Object
Get a value from a hash, with some special handling of self references
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# File 'lib/fhir_models/fhirpath/evaluate.rb', line 16 def self.get(key, hash) return @@context if ['$context', '$resource'].include?(key) return @@parent if key == '$parent' return 'http://unitsofmeasure.org' if key == '%ucum' return 'http://snomed.info/sct' if key == '%sct' return 'http://loinc.org' if key == '%loinc' return key.gsub!(/\A\'|\'\Z/, '') if key.start_with?("'") && key.end_with?("'") key.gsub!(/\A"|"\Z/, '') # remove quotes around path if they exist if hash.is_a?(Array) response = [] hash.each do |e| next unless e.is_a?(Hash) item = e[key] if item.is_a?(Array) item.each { |i| response << i } else response << item end end return response end return :null unless hash.is_a?(Hash) return hash if hash['resourceType'] == key val = hash[key] if val.nil? # this block is a dangerous hack to get fields of multiple data types # e.g. 'value' instead of 'valueQuantity', or 'onset' instead of 'onsetDateTime' or 'onsetPeriod' nkey = hash.keys.select { |x| x.start_with?(key) }.first unless nkey.nil? tail = nkey.gsub(key, '') val = hash[nkey] if tail[0] == tail[0].capitalize end end val = :null if val.nil? val = "'#{val}'" if val.is_a?(String) && !(val.start_with?("'") && val.end_with?("'")) val end |
.parse(expression) ⇒ Object
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# File 'lib/fhir_models/fhirpath/parse.rb', line 4 def self.parse(expression) build_tree(tokenize(expression)) end |
.reassemble_strings(tokens) ⇒ Object
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# File 'lib/fhir_models/fhirpath/parse.rb', line 44 def self.reassemble_strings(tokens) tokens.each_with_index do |token, index| next unless token.is_a?(String) e_index = nil if token.start_with?('"') && !token.end_with?('"') e_index = tokens[index..-1].index { |t| t.end_with?('"') } elsif token.start_with?("'") && !token.end_with?("'") e_index = tokens[index..-1].index { |t| t.end_with?("'") } end next unless e_index i = index + 1 while i <= index + e_index tokens[index] += tokens[i] tokens[i] = '' i += 1 end end end |
.tokenize(expression) ⇒ Object
This method tokenizes the expression into a flat array of tokens
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# File 'lib/fhir_models/fhirpath/parse.rb', line 9 def self.tokenize(expression) raw_tokens = expression.gsub('()', '').split(%r{(\(|\)|\s|>=|<=|>|<|=|!=|\+|-|\/|\*)}) # recreate strings if they were split size = nil while raw_tokens.include?("'") && size != raw_tokens.length index = raw_tokens.index("'") e_index = raw_tokens[(index + 1)..raw_tokens.length].index("'") raw_tokens[index] = raw_tokens[index..(index + e_index + 1)].join ((index + 1)..(index + e_index + 1)).each { |i| raw_tokens[i] = nil } raw_tokens.compact! size = raw_tokens.length end # reassemble strings that might have been inadvertently split that start and end with double-quotes reassemble_strings(raw_tokens) tokens = [] raw_tokens.each do |token| # split a path unless it is quoted if token.include?('.') && !(token.start_with?("'") && token.end_with?("'")) token.split('.').each { |t| tokens << t } # split arrays and replace with array elsif token.include?('|') array = [] token.split('|').each { |t| array << t.delete('\'') } tokens << array else tokens << token end end # we may need to reassemble quoted strings again reassemble_strings(tokens) tokens.delete_if { |token| (token.length.zero? || (token.is_a?(String) && token.match(/\S/).nil?)) } FHIR.logger.debug "TOKENS: #{tokens}" tokens end |