class CompilationEngine:
###############
# CONSTRUCTOR #
###############
def __init__(self, in_filename, in_file, out_xml, out_vm):
"""
Creates a new compilation engine with the given input and output.
The next routine called must be compileClass().
:param in_file: Open source Jack file.
:param out_xml: Open XML file.
:param out_vm: Open VM file.
"""
self.__in_filename = in_filename
self.__in_file, self.__out_xml = in_file, out_xml
self.__tokenizer = JackTokenizer(in_file)
self.__symbolTable = SymbolTable()
self.__vmWriter = VMWriter(in_filename, out_vm)
self.__stack = list()
self.__tokenizer.advance()
self.__resetUniqueLabels()
###################
# PRIVATE METHODS #
###################
def __resetUniqueLabels(self):
self.__unique_id_if = 0
self.__unique_id_while = 0
def __uniqueWhileLabels(self):
"""
Return (IF_TRUE, IF_FALSE, IF_END) labels carrying a unique id to
prevent collisions with other labels carrying the same name.
Example:
while_exp, while_end = __uniqueWhileLabels()
-->
while_exp = "WHILE_EXP123"
while_end = "WHILE_END123"
"""
unique_labels = []
for label in [WHILE_EXP, WHILE_END]:
unique_labels.append("{}{}{}".format(label, UNIQUE_DELIMITER,
self.__unique_id_while))
self.__unique_id_while += 1
return unique_labels
def __uniqueIfLabels(self):
"""
Return (IF_TRUE, IF_FALSE, IF_END) labels carrying a unique id to
prevent collisions with other labels carrying the same name.
Example:
if_true, if_false, if_end = __uniqueIfLabels()
-->
if_true = "IF_TRUE123"
if_false = "IF_FALSE123"
if_end = "IF_END123"
"""
unique_labels = []
for label in [IF_TRUE, IF_FALSE, IF_END]:
unique_labels.append("{}{}{}".format(label, UNIQUE_DELIMITER,
self.__unique_id_if))
self.__unique_id_if += 1
return unique_labels
def __writeToken(self, token, token_type):
"""
Writes the given token as an xml tag to the output.
:param token:
:param token_type:
:return:
"""
tag = self.__getIndentedTag("<{0}>{1}{2}{1}</{0}>\n".format(
token_type, XML_DELIM_TERMINAL, token))
self.__out_xml.write(tag)
def __writeTokenAndAdvance(self, token, token_type):
"""
Writes the given token as an xml tag to the output and extracts the
next token from the code.
:param token: token tag value
:param token_type: token tag type
"""
# Build XML tag
self.__writeToken(token, token_type)
self.__tokenizer.advance()
def __getIndentedTag(self, tag):
"""
Return the given tag with trailing tabs according to current
indentation level.
:param tag: tag to indent
:return: tag indented with trailing tabs.
"""
return XML_INDENT_CHAR * len(self.__stack) + tag
def __openTag(self, tagName):
"""
Open an XML tag with the given name.
All following tags will be written as inner tags until __closeTag()
is called.
:param tagName: name of the tag to open
"""
tag = self.__getIndentedTag("<{}>\n".format(tagName))
self.__out_xml.write(tag)
self.__stack.append(tagName)
def __closeTag(self):
"""
Close the current open XML tag.
All following tags will be written as outer tags in the previous
indentation level.
"""
tagName = self.__stack.pop()
tag = self.__getIndentedTag("</{}>\n".format(tagName))
self.__out_xml.write(tag)
def __compileKeyWord(self):
"""
Compile a keyword token
"""
keyword = self.__tokenizer.keyWord()
self.__writeTokenAndAdvance(keyword, TOKEN_TYPE_KEYWORD)
return keyword
def __compileSymbol(self):
"""
Compile a symbol token
"""
symbol = self.__tokenizer.symbol()
self.__writeTokenAndAdvance(symbol, TOKEN_TYPE_SYMBOL)
return symbol
def __compileIdentifier(self,
category,
status,
kind=KIND_NONE,
index=INDEX_NONE):
"""
Compile an identifier token
"""
info = "{} {}".format(category, status)
if kind != KIND_NONE:
info += " " + KIND_2_SEGMENT[kind]
if index != INDEX_NONE:
info += " " + str(index)
info = "[{}] ".format(info)
identifier = self.__tokenizer.identifier()
self.__writeTokenAndAdvance(info + identifier, TOKEN_TYPE_IDENTIFIER)
return identifier
def __compileIntVal(self):
"""
Compile an intVal token
"""
intval = self.__tokenizer.intVal()
self.__writeTokenAndAdvance(intval, TOKEN_TYPE_INTEGER)
self.__vmWriter.writePush(VM_SEGMENT_CONSTANT, intval)
return intval
def __compileStringVal(self):
"""
Compile a stringVal token
"""
string = self.__tokenizer.stringVal()
self.__writeTokenAndAdvance(string, TOKEN_TYPE_STRING)
corrected = self.__correctString(string)
self.__vmWriter.writePush(VM_SEGMENT_CONSTANT, len(corrected))
self.__vmWriter.writeCall(OS_STRING_NEW, 1)
for char in corrected:
self.__vmWriter.writePush(VM_SEGMENT_CONSTANT, ord(char))
self.__vmWriter.writeCall(OS_STRING_APPEND_CHAR, 2)
def __compileClassName(self, status):
"""
Compiles a variable name.
"""
return self.__compileIdentifier(CATEGORY_CLASS, status)
def __compileSubroutineName(self, status):
"""
Compiles a variable name.
"""
return self.__compileIdentifier(CATEGORY_SUBROUTINE, status)
def __compileSubroutineCall(self):
"""
Compiles a subroutine call.
Syntax:
( className | varName) '.' subroutineName '(' expressionList ')' |
subroutineName '(' expressionList ')'
"""
# Compile XML
callName = ""
exp_count = 0
if self.__tokenizer.lookahead() == RE_DOT: # className | varName
# extract var\class name
callName = self.__tokenizer.peek()
# className or varName?
kind = self.__symbolTable.kindOf(callName)
if (kind != KIND_NONE): # varName
# Use class name instead of object name
varName = callName
callName = self.__symbolTable.typeOf(callName)
# Push variable (this) and call class method
index = self.__symbolTable.indexOf(varName)
segment = self.__symbolTable.segmentOf(varName)
self.__vmWriter.writePush(segment, index)
# Include self as argument 0
exp_count += 1
self.__compileIdentifier(kind, STATUS_USE, kind, index)
else: # className
self.__compileIdentifier(CATEGORY_CLASS, STATUS_USE)
callName += self.__compileSymbol() # '.'
else: # subroutineName
# Subroutine -> className.Subroutine
self.__vmWriter.writePush(VM_SEGMENT_POINTER, 0)
callName += self.__className + FUNC_NAME_DELIMITER
exp_count += 1
callName += self.__compileSubroutineName(STATUS_USE)
self.__compileSymbol() # '('
exp_count += self.CompileExpressionList() # expressionList
self.__compileSymbol() # ')'
# Compile VM
self.__vmWriter.writeCall(callName, exp_count)
def __compileVarName(self, status):
"""
Compiles a variable name.
"""
name = self.__tokenizer.peek()
index = INDEX_NONE
if status != STATUS_DEFINE:
index = self.__symbolTable.indexOf(name)
varName = self.__compileIdentifier(CATEGORY_VAR, status, KIND_VAR,
index)
return varName
def __compileType(self):
"""
Compiles a type.
Syntax:
'int' | 'char' | 'boolean' | className
"""
# 'int' | 'char' | 'boolean'
if self.__tokenizer.peek() in {RE_INT, RE_CHAR, RE_BOOLEAN}:
type = self.__compileKeyWord()
# className
else:
type = self.__compileClassName(STATUS_USE)
return type
def __compileSubroutineBody(self, funcType, name):
"""
Compiles a subroutine body.
Syntax:
'{' varDec* statements '}'
"""
self.__openTag('subroutineBody') # <subroutineBody>
self.__compileSymbol() # '{'
# varDec*
while self.__tokenizer.peek() == RE_VAR:
self.compileVarDec() # varDec*
vars = self.__symbolTable.varCount(KIND_VAR)
self.__vmWriter.writeFunction(name, vars)
if funcType == RE_METHOD:
# Hold self at pointer
self.__vmWriter.writePush(VM_SEGMENT_ARGUMENT, 0)
self.__vmWriter.writePop(VM_SEGMENT_POINTER, 0)
if funcType == RE_CONSTRUCTOR:
# Allocate memory for all fields
fields = self.__symbolTable.varCount(KIND_FIELD)
self.__vmWriter.writePush(VM_SEGMENT_CONSTANT, fields)
self.__vmWriter.writeCall(OS_MEMORY_ALLOC, 1)
# Hold allocated memory at pointer
self.__vmWriter.writePop(VM_SEGMENT_POINTER, 0)
self.compileStatements() # statements
self.__compileSymbol() # '}'
self.__closeTag() # </subroutineBody>
return vars
##################
# PUBLIC METHODS #
##################
def compileClass(self):
"""
Compiles a complete class.
Syntax:
'class' className '{' classVarDec* subroutineDec* '}'
"""
self.__openTag('class') # <class>
self.__compileKeyWord() # 'class'
className = self.__compileClassName( # className
STATUS_DEFINE)
self.__className = className
self.__compileSymbol() # '{'
# classVarDec*
while self.__tokenizer.peek() in {RE_STATIC, RE_FIELD}:
self.CompileClassVarDec()
# subroutineDec*
while self.__tokenizer.peek() in {
RE_CONSTRUCTOR, RE_FUNCTION, RE_METHOD
}:
self.CompileSubroutine()
self.__compileSymbol() # '}'
self.__closeTag() # </class>
def CompileClassVarDec(self):
"""
Compiles a static declaration or a field declaration.
Syntax:
('static' | 'field') type varName (',' varName)* ';'
"""
self.__openTag('classVarDec') # <classVarDec>
kind = self.__compileKeyWord() # ('static' | 'field')
type = self.__compileType() # type
moreVars = True
while moreVars: # (',' varName)*
name = self.__compileVarName( # varName
STATUS_DEFINE)
self.__symbolTable.define(name, type, kind)
if self.__tokenizer.peek() != RE_COMMA:
moreVars = False
else:
self.__compileSymbol() # ','
self.__compileSymbol() # ';'
self.__closeTag() # </classVarDec>
def CompileSubroutine(self):
"""
Compiles a complete method, function, or constructor.
Syntax:
('constructor' | 'function' | 'method') ('void' | type)
subroutineName '(' parameterList ')' subroutineBody
"""
# Start subroutine in symbol table
self.__resetUniqueLabels()
self.__symbolTable.startSubroutine()
# Compile XML
self.__openTag('subroutineDec') # <subroutineDec>
funcType = self.__compileKeyWord() # ('constructor' |
# 'function' | 'method')
if funcType in {RE_METHOD}:
# +1 var count for this method (+1 for self)
self.__symbolTable.define(VM_SELF, self.__className, KIND_ARG)
if self.__tokenizer.peek() == RE_VOID:
type = self.__compileKeyWord() # 'void'
else:
type = self.__compileType() # type
subName = self.__compileSubroutineName( # soubroutineName
STATUS_DEFINE)
name = self.__className + FUNC_NAME_DELIMITER + subName
self.__compileSymbol() # '('
self.compileParameterList() # parameterList
self.__compileSymbol() # ')'
self.__compileSubroutineBody(funcType, name) # subroutineBody
self.__closeTag() # </subroutineDec>
def compileParameterList(self):
"""
Compiles a (possibly empty) parameter list, not including the
enclosing "()".
Syntax:
( (type varName) (',' type varName)*)?
"""
parameters = 0 # no parameters?
self.__openTag('parameterList') # <parameterList>
if self.__tokenizer.peek() != RE_BRACKETS_RIGHT:
moreVars = True
while moreVars:
parameters += 1 # yes parameters!
type = self.__compileType() # type
name = self.__compileVarName( # varName
STATUS_DEFINE)
self.__symbolTable.define(name, type, KIND_ARG)
if self.__tokenizer.peek() == RE_COMMA:
self.__compileSymbol() # ','
else:
moreVars = False
self.__closeTag() # </parametersList>
return parameters
def compileVarDec(self):
"""
Compiles a var declaration.
Syntax:
'var' type varName (',' varName)* ';'
"""
self.__openTag('varDec') # <varDec>
moreVars = True
self.__compileKeyWord() # 'var'
type = self.__compileType() # type
while moreVars:
name = self.__tokenizer.peek() # varName
self.__symbolTable.define(name, type, KIND_VAR)
self.__compileVarName(STATUS_DEFINE)
if self.__tokenizer.peek() == RE_COMMA:
self.__compileSymbol() # ','
else:
moreVars = False
self.__compileSymbol() # ';'
self.__closeTag() # </varDec>
def compileStatements(self):
"""
Compiles a sequence of statements, not including the enclosing "{}".
Syntax:
statement*
where statement is in:
letStatement | ifStatement | whileStatement | doStatement | returnStatement
"""
self.__openTag('statements') # <statements>
statement = self.__tokenizer.peek()
while statement in {
RE_LET, RE_IF, RE_WHILE, RE_DO, RE_RETURN_NOTHING,
RE_RETURN_SOMETHING
}:
if statement == RE_LET:
self.compileLet()
elif statement == RE_IF:
self.compileIf()
elif statement == RE_WHILE:
self.compileWhile()
elif statement == RE_DO:
self.compileDo()
elif statement == RE_RETURN_NOTHING:
self.compileReturnNothing()
elif statement == RE_RETURN_SOMETHING:
self.compileReturnSomething()
statement = self.__tokenizer.peek()
self.__closeTag() # </statements>
def compileDo(self):
"""
Compiles a do statement.
Syntax:
'do' subroutineCall ';'
"""
self.__openTag('doStatement') # <doStatement>
self.__compileKeyWord() # 'do'
self.__compileSubroutineCall() # subroutineCall
self.__vmWriter.writePop(VM_SEGMENT_TEMP, 0)
self.__compileSymbol() # ';'
self.__closeTag() # </doStatement>
def compileLet(self):
"""
Compiles a let statement.
Syntax:
'let' varName ('[' expression ']')? '=' expression ';'
"""
isArray = False
self.__openTag('letStatement') # <letStatement>
self.__compileKeyWord() # 'let'
varName = self.__tokenizer.peek()
index = self.__symbolTable.indexOf(varName)
segment = self.__symbolTable.segmentOf(varName)
self.__compileVarName(STATUS_USE) # varName
if self.__tokenizer.peek() == RE_BRACKETS_SQUARE_LEFT:
isArray = True
self.__compileSymbol() # '['
self.CompileExpression() # expression
self.__compileSymbol() # ']'
# Add the offset to the variable address
self.__vmWriter.writePush(segment, index)
self.__vmWriter.writeArithmetic(RE_PLUS, True)
# Address of array element is at stack top
self.__compileSymbol() # '='
self.CompileExpression() # expression
self.__compileSymbol() # ';'
self.__closeTag() # </letStatement>
if isArray:
# Pop rh-expression to temp
self.__vmWriter.writePop(VM_SEGMENT_TEMP, 0)
# Get address of array element
self.__vmWriter.writePop(VM_SEGMENT_POINTER, 1)
# Push rh-expression to stack
self.__vmWriter.writePush(VM_SEGMENT_TEMP, 0)
# Pop rh-expression to address of element
self.__vmWriter.writePop(VM_SEGMENT_THAT, 0)
else:
# Compile only if the varName was defined
# (unlike class name of subroutine name)
# if segment != KIND_NONE: # varName was defined
index = self.__symbolTable.indexOf(varName)
self.__vmWriter.writePop(segment, index)
def compileWhile(self):
"""
Compiles a while statement.
Syntax:
'while' '(' expression ')' '{' statements '}'
"""
LABEL_EXP, LABEL_END = self.__uniqueWhileLabels()
self.__openTag('whileStatement') # <whileStatement>
self.__compileKeyWord() # 'while'
self.__compileSymbol() # '('
self.__vmWriter.writeLabel( # label WHILE_EXP
LABEL_EXP)
self.CompileExpression() # expression
# Negate the expression
# (jump out of while if *NOT* expression)
self.__vmWriter.writeArithmetic(RE_TILDA, False)
self.__compileSymbol() # ')'
self.__vmWriter.writeIf(LABEL_END) # if-goto WHILE_END
self.__compileSymbol() # '{'
self.compileStatements() # statements
self.__compileSymbol() # '}'
self.__vmWriter.writeGoto(LABEL_EXP) # goto WHILE_EXP
self.__vmWriter.writeLabel(LABEL_END) # lable WHILE_END
self.__closeTag() # </whileStatement>
def compileReturnNothing(self):
"""
Compiles a 'return;' statement.
Syntax:
'return;'
"""
# Compile XML
self.__openTag('returnStatement') # <returnStatement>
self.__writeToken(
'return', # 'return'
TOKEN_TYPE_KEYWORD)
self.__writeTokenAndAdvance(
';', # ';'
TOKEN_TYPE_SYMBOL)
self.__vmWriter.writeReturn(True)
self.__closeTag() # </returnStatement>
def compileReturnSomething(self):
"""
Compiles a return statement.
Syntax:
'return' expression? ';'
"""
# Compile XML
self.__openTag('returnStatement') # <returnStatement>
self.__writeTokenAndAdvance(
'return', # 'return'
TOKEN_TYPE_KEYWORD)
self.CompileExpression() # expression
self.__compileSymbol() # ';'
self.__vmWriter.writeReturn()
self.__closeTag() # </returnStatement>
def compileIf(self):
"""
Compiles an if statement, possibly with a trailing else clause.
Syntax:
'if' '(' expression ')' '{' statements '}' ( 'else' '{' statements
'}' )?
"""
LABEL_TRUE, LABEL_FALSE, LABEL_END = self.__uniqueIfLabels()
self.__openTag('ifStatement') # <ifStatement>
self.__compileKeyWord() # 'if'
self.__compileSymbol() # '('
# VM Code for computing ~(cond)
self.CompileExpression() # expression
self.__compileSymbol() # ')'
self.__vmWriter.writeIf(LABEL_TRUE) # if-goto LABEL_TRUE
self.__vmWriter.writeGoto(LABEL_FALSE) # goto LABEL_FALSE
self.__vmWriter.writeLabel(LABEL_TRUE) # label LABEL_TRUE
self.__compileSymbol() # '{'
# VM Code for executing TRUE
self.compileStatements() # statements
self.__compileSymbol() # '}'
if self.__tokenizer.peek() == RE_ELSE: #
self.__vmWriter.writeGoto(LABEL_END) # goto LABEL_END
self.__vmWriter.writeLabel( # label LABEL_FALSE
LABEL_FALSE)
self.__compileKeyWord() # 'else'
self.__compileSymbol() # '{'
# VM Code for executing ELSE
self.compileStatements() # statements
self.__compileSymbol() # '}'
self.__vmWriter.writeLabel( # label END
LABEL_END)
else:
self.__vmWriter.writeLabel( # label FALSE
LABEL_FALSE)
self.__closeTag() # </ifStatement>
def CompileExpression(self):
"""
Compiles an expression.
Syntax:
term (op term)*
"""
self.__openTag('expression') # <expression>
self.CompileTerm() # term
while self.__tokenizer.peek() in {
RE_PLUS, RE_BAR, RE_ASTERISK, RE_SLASH, RE_AMPERSAND, RE_VBAR,
RE_LT, RE_GT, RE_EQ
}:
symbol = self.__compileSymbol() # op
self.CompileTerm() # term
self.__vmWriter.writeSymbol(symbol)
self.__closeTag() # </expression>
def __correctString(self, string):
"""
Convert escape characters in a string to valid chars
:param string: string to correct
:return: corrected strings with escaped characters corrected
"""
correct = string.replace('\t', '\\t')
correct = correct.replace('\n', '\\n')
correct = correct.replace('\r', '\\r')
return correct
def CompileTerm(self):
"""
Compiles a term.
This routine is faced with a slight difficulty when trying to decide
between some of the alternative parsing rules.
Specifically, if the current token is an identifier, the routine
must distinguish between a variable, an array entry, and a subroutine
call. A single look-ahead token, which may be one
of "[", "(", or "." suffices to distinguish between the three
possibilities. Any other token is not part of this term and should
not be advanced over.
Syntax:
integerConstant | stringConstant | keywordConstant | varName |
varName '[' expression ']' | subroutineCall | '(' expression ')' |
unaryOp term
"""
self.__openTag('term') # <term>
lookahead = self.__tokenizer.lookahead()
if self.__tokenizer.peek() == RE_BRACKETS_LEFT:
self.__compileSymbol() # '('
self.CompileExpression() # expression
self.__compileSymbol() # ')'
elif self.__tokenizer.peek() in {RE_TILDA, RE_BAR}:
symbol = self.__compileSymbol() # unaryOp
self.CompileTerm() # term
self.__vmWriter.writeArithmetic(symbol, False)
elif lookahead == RE_BRACKETS_SQUARE_LEFT:
varName = self.__tokenizer.peek()
self.__compileVarName(STATUS_USE) # varName
self.__compileSymbol() # '['
self.CompileExpression() # expression
self.__compileSymbol() # ']'
# Compile array indexing
kind = self.__symbolTable.kindOf(varName)
index = self.__symbolTable.indexOf(varName)
segment = KIND_2_SEGMENT[kind]
self.__vmWriter.writePush(segment, index)
self.__vmWriter.writeArithmetic(RE_PLUS, True)
self.__vmWriter.writePop(VM_SEGMENT_POINTER, 1)
self.__vmWriter.writePush(VM_SEGMENT_THAT, 0)
elif lookahead in {RE_BRACKETS_LEFT, RE_DOT}:
self.__compileSubroutineCall() # subroutineCall |
# (varName | className) '.' subroutineCall
else:
if self.__tokenizer.tokenType() == TOKEN_TYPE_INTEGER:
self.__compileIntVal() # integerConstant
elif self.__tokenizer.tokenType() == TOKEN_TYPE_STRING:
self.__compileStringVal() # stringConstant
elif self.__tokenizer.tokenType() == TOKEN_TYPE_KEYWORD:
# true | false | null | this
# true | false | null - pushed to stack as constants
keyword = self.__tokenizer.peek()
if keyword in {RE_FALSE, RE_NULL, RE_TRUE}:
self.__vmWriter.writePush(VM_SEGMENT_CONSTANT, 0)
if keyword == RE_TRUE:
self.__vmWriter.writeArithmetic(RE_TILDA, False)
# this - pushes pointer
elif keyword == RE_THIS:
self.__vmWriter.writePush(VM_SEGMENT_POINTER, 0)
self.__compileKeyWord() # keywordConstant
elif self.__tokenizer.tokenType() == TOKEN_TYPE_IDENTIFIER:
name = self.__tokenizer.peek()
kind = self.__symbolTable.kindOf(name)
index = self.__symbolTable.indexOf(name)
segment = self.__symbolTable.segmentOf(name)
self.__compileIdentifier(kind, STATUS_USE, kind, index)
self.__vmWriter.writePush(segment, index)
self.__closeTag() # </term>
def CompileExpressionList(self):
"""
Compiles a (possibly empty) comma-separated list of expressions.
Syntax:
(expression (',' expression)* )?
"""
exp_count = 0
self.__openTag('expressionList') # <expressionList>
if self.__tokenizer.peek() != RE_BRACKETS_RIGHT:
self.CompileExpression()
exp_count += 1 # expression
while self.__tokenizer.peek() == RE_COMMA:
self.__compileSymbol() # ','
self.CompileExpression()
exp_count += 1
self.__closeTag() # </expressionList>
return exp_count
