Removed files no longer needed.
This commit is contained in:
Fred Drake
parent
3c1b4a40dc
commit
19405a4a2a
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@ -1,30 +0,0 @@
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# Lame substitute for a fine script to generate the table from ast.txt
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from compiler import astgen
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AST_DEF = '../compiler/ast.txt'
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def sort(l):
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l = l[:]
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l.sort(lambda a, b: cmp(a.name, b.name))
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return l
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def main():
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nodes = astgen.parse_spec(AST_DEF)
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print "\\begin{longtableiii}{lll}{class}{Node type}{Attribute}{Value}"
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print
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for node in sort(nodes):
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if node.argnames:
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print "\\lineiii{%s}{%s}{}" % (node.name, node.argnames[0])
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else:
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print "\\lineiii{%s}{}{}" % node.name
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for arg in node.argnames[1:]:
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print "\\lineiii{}{\\member{%s}}{}" % arg
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print "\\hline", "\n"
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print "\\end{longtableiii}"
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if __name__ == "__main__":
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main()
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@ -1,253 +0,0 @@
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\begin{longtableiii}{lll}{class}{Node type}{Attribute}{Value}
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\lineiii{Add}{\member{left}}{left operand}
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\lineiii{}{\member{right}}{right operand}
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\hline
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\lineiii{And}{\member{nodes}}{list of operands}
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\hline
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\lineiii{AssAttr}{}{\emph{attribute as target of assignment}}
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\lineiii{}{\member{expr}}{expression on the left-hand side of the dot}
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\lineiii{}{\member{attrname}}{the attribute name, a string}
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\lineiii{}{\member{flags}}{XXX}
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\hline
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\lineiii{AssList}{\member{nodes}}{list of list elements being assigned to}
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\hline
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\lineiii{AssName}{\member{name}}{name being assigned to}
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\lineiii{}{\member{flags}}{XXX}
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\hline
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\lineiii{AssTuple}{\member{nodes}}{list of tuple elements being assigned to}
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\hline
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\lineiii{Assert}{\member{test}}{the expression to be tested}
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\lineiii{}{\member{fail}}{the value of the \exception{AssertionError}}
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\hline
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\lineiii{Assign}{\member{nodes}}{a list of assignment targets, one per equal sign}
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\lineiii{}{\member{expr}}{the value being assigned}
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\hline
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\lineiii{AugAssign}{\member{node}}{}
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\lineiii{}{\member{op}}{}
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\lineiii{}{\member{expr}}{}
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\hline
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\lineiii{Backquote}{\member{expr}}{}
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\hline
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\lineiii{Bitand}{\member{nodes}}{}
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\hline
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\lineiii{Bitor}{\member{nodes}}{}
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\hline
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\lineiii{Bitxor}{\member{nodes}}{}
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\hline
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\lineiii{Break}{}{}
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\hline
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\lineiii{CallFunc}{\member{node}}{expression for the callee}
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\lineiii{}{\member{args}}{a list of arguments}
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\lineiii{}{\member{star_args}}{the extended *-arg value}
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\lineiii{}{\member{dstar_args}}{the extended **-arg value}
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\hline
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\lineiii{Class}{\member{name}}{the name of the class, a string}
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\lineiii{}{\member{bases}}{a list of base classes}
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\lineiii{}{\member{doc}}{doc string, a string or \code{None}}
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\lineiii{}{\member{code}}{the body of the class statement}
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\hline
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\lineiii{Compare}{\member{expr}}{}
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\lineiii{}{\member{ops}}{}
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\hline
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\lineiii{Const}{\member{value}}{}
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\hline
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\lineiii{Continue}{}{}
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\hline
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\lineiii{Dict}{\member{items}}{}
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\hline
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\lineiii{Discard}{\member{expr}}{}
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\hline
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\lineiii{Div}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Ellipsis}{}{}
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\hline
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\lineiii{Exec}{\member{expr}}{}
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\lineiii{}{\member{locals}}{}
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\lineiii{}{\member{globals}}{}
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\hline
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\lineiii{For}{\member{assign}}{}
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\lineiii{}{\member{list}}{}
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\lineiii{}{\member{body}}{}
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\lineiii{}{\member{else_}}{}
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\hline
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\lineiii{From}{\member{modname}}{}
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\lineiii{}{\member{names}}{}
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\hline
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\lineiii{Function}{\member{name}}{name used in def, a string}
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\lineiii{}{\member{argnames}}{list of argument names, as strings}
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\lineiii{}{\member{defaults}}{list of default values}
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\lineiii{}{\member{flags}}{xxx}
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\lineiii{}{\member{doc}}{doc string, a string or \code{None}}
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\lineiii{}{\member{code}}{the body of the function}
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\hline
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\lineiii{Getattr}{\member{expr}}{}
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\lineiii{}{\member{attrname}}{}
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\hline
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\lineiii{Global}{\member{names}}{}
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\hline
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\lineiii{If}{\member{tests}}{}
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\lineiii{}{\member{else_}}{}
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\hline
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\lineiii{Import}{\member{names}}{}
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\hline
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\lineiii{Invert}{\member{expr}}{}
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\hline
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\lineiii{Keyword}{\member{name}}{}
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\lineiii{}{\member{expr}}{}
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\hline
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\lineiii{Lambda}{\member{argnames}}{}
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\lineiii{}{\member{defaults}}{}
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\lineiii{}{\member{flags}}{}
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\lineiii{}{\member{code}}{}
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\hline
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\lineiii{LeftShift}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{List}{\member{nodes}}{}
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\hline
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\lineiii{ListComp}{\member{expr}}{}
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\lineiii{}{\member{quals}}{}
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\hline
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\lineiii{ListCompFor}{\member{assign}}{}
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\lineiii{}{\member{list}}{}
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\lineiii{}{\member{ifs}}{}
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\hline
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\lineiii{ListCompIf}{\member{test}}{}
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\hline
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\lineiii{Mod}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Module}{\member{doc}}{doc string, a string or \code{None}}
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\lineiii{}{\member{node}}{body of the module, a \class{Stmt}}
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\hline
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\lineiii{Mul}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Name}{\member{name}}{}
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\hline
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\lineiii{Not}{\member{expr}}{}
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\hline
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\lineiii{Or}{\member{nodes}}{}
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\hline
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\lineiii{Pass}{}{}
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\hline
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\lineiii{Power}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Print}{\member{nodes}}{}
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\lineiii{}{\member{dest}}{}
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\hline
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\lineiii{Printnl}{\member{nodes}}{}
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\lineiii{}{\member{dest}}{}
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\hline
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\lineiii{Raise}{\member{expr1}}{}
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\lineiii{}{\member{expr2}}{}
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\lineiii{}{\member{expr3}}{}
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\hline
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\lineiii{Return}{\member{value}}{}
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\hline
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\lineiii{RightShift}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Slice}{\member{expr}}{}
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\lineiii{}{\member{flags}}{}
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\lineiii{}{\member{lower}}{}
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\lineiii{}{\member{upper}}{}
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\hline
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\lineiii{Sliceobj}{\member{nodes}}{list of statements}
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\hline
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\lineiii{Stmt}{\member{nodes}}{}
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\hline
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\lineiii{Sub}{\member{left}}{}
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\lineiii{}{\member{right}}{}
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\hline
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\lineiii{Subscript}{\member{expr}}{}
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\lineiii{}{\member{flags}}{}
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\lineiii{}{\member{subs}}{}
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\hline
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\lineiii{TryExcept}{\member{body}}{}
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\lineiii{}{\member{handlers}}{}
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\lineiii{}{\member{else_}}{}
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\hline
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\lineiii{TryFinally}{\member{body}}{}
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\lineiii{}{\member{final}}{}
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\hline
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\lineiii{Tuple}{\member{nodes}}{}
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\hline
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\lineiii{UnaryAdd}{\member{expr}}{}
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\hline
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\lineiii{UnarySub}{\member{expr}}{}
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\hline
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\lineiii{While}{\member{test}}{}
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\lineiii{}{\member{body}}{}
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\lineiii{}{\member{else_}}{}
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\hline
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\lineiii{Yield}{\member{value}}{}
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\hline
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\end{longtableiii}
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@ -1,380 +0,0 @@
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% Complete documentation on the extended LaTeX markup used for Python
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% documentation is available in ``Documenting Python'', which is part
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% of the standard documentation for Python. It may be found online
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% at:
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%
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% http://www.python.org/doc/current/doc/doc.html
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\documentclass{howto}
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\title{Python compiler package}
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\author{Jeremy Hylton}
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% Please at least include a long-lived email address;
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% the rest is at your discretion.
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\authoraddress{
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PythonLabs \\
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Zope Corporation \\
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Email: \email{jeremy@zope.com}
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}
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\date{August 15, 2001} % update before release!
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% Use an explicit date so that reformatting
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% doesn't cause a new date to be used. Setting
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% the date to \today can be used during draft
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% stages to make it easier to handle versions.
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\release{2.2} % release version; this is used to define the
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% \version macro
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\makeindex % tell \index to actually write the .idx file
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\makemodindex % If this contains a lot of module sections.
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\begin{document}
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\maketitle
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\begin{abstract}
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\noindent
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The Python compiler package is a tool for analyzing Python source code
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and generating Python bytecode. The compiler contains libraries to
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generate an abstract syntax tree from Python source code and to
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generate Python bytecode from the tree.
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\end{abstract}
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\tableofcontents
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\section{Introduction\label{Introduction}}
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The \module{compiler} package is a Python source to bytecode
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translator written in Python. It uses the builtin parser and standard
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\ulink{\module{parser}}
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{http://www.python.org/doc/current/lib/module-parser.html} to
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generated a concrete syntax tree. This tree is used to generate an
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abstract syntax tree (AST) and then Python bytecode.
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The full functionality of the package duplicates the builtin compiler
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provided with the Python interpreter. It is intended to match its
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behavior almost exactly. Why implement another compiler that does the
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same thing? The package is useful for a variety of purposes. It can
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be modified more easily than the builtin compiler. The AST it
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generates is useful for analyzing Python source code.
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This manual explains how the various components of the
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\module{compiler} package work. It blends reference material with a
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tutorial. (At least it will when the document is done.)
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\subsection{The basic interface}
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\declaremodule{}{compiler}
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The top-level of the package defines four functions. If you import
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\module{compiler}, you will get these functions and a collection of
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modules contained in the package.
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\begin{funcdesc}{parse}{buf}
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Returns an abstract syntax tree for the Python source code in \var{buf}.
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The function raises SyntaxError if there is an error in the source
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code. The return value is a \class{compiler.ast.Module} instance that
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contains the tree.
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\end{funcdesc}
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\begin{funcdesc}{parseFile}{path}
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Return an abstract syntax tree for the Python source code in the file
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specified by \var{path}. It is equivalent to
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\code{parse(open(\var{path}).read())}.
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\end{funcdesc}
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\begin{funcdesc}{walk}{ast, visitor\optional{, verbose}}
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Do a pre-order walk over the abstract syntax tree \var{ast}. Call the
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appropriate method on the \var{visitor} instance for each node
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encountered.
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\end{funcdesc}
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\begin{funcdesc}{compile}{path}
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Compile the file \var{path} and generate the corresponding \file{.pyc}
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file.
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\end{funcdesc}
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The \module{compiler} package contains the following modules:
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\refmodule[compiler.ast]{ast}, \module{consts}, \module{future},
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\module{misc}, \module{pyassem}, \module{pycodegen}, \module{symbols},
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\module{transformer}, and \refmodule[compiler.visitor]{visitor}.
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\subsection{Limitations}
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There are some problems with the error checking of the compiler
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package. The interpreter detects syntax errors in two distinct
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phases. One set of errors is detected by the interpreter's parser,
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the other set by the compiler. The compiler package relies on the
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interpreter's parser, so it get the first phases of error checking for
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free. It implements the second phase itself, and that implement is
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incomplete. For example, the compiler package does not raise an error
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if a name appears more than once in an argument list:
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\code{def f(x, x): ...}
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A future version of the compiler should fix these problems.
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\section{Python Abstract Syntax}
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The \module{compiler.ast} module defines an abstract syntax for
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Python. In the abstract syntax tree, each node represents a syntactic
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construct. The root of the tree is \class{Module} object.
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The abstract syntax offers a higher level interface to parsed Python
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source code. The \ulink{\module{parser}}
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{http://www.python.org/doc/current/lib/module-parser.html}
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module and the compiler written in C for the Python interpreter use a
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concrete syntax tree. The concrete syntax is tied closely to the
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grammar description used for the Python parser. Instead of a single
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node for a construct, there are often several levels of nested nodes
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that are introduced by Python's precedence rules.
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The abstract syntax tree is created by the
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\module{compiler.transformer} module. The transformer relies on the
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builtin Python parser to generate a concrete syntax tree. It
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generates an abstract syntax tree from the concrete tree.
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The \module{transformer} module was created by Greg
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Stein\index{Stein, Greg} and Bill Tutt\index{Tutt, Bill} for an
|
||||
experimental Python-to-C compiler. The current version contains a
|
||||
number of modifications and improvements, but the basic form of the
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||||
abstract syntax and of the transformer are due to Stein and Tutt.
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\subsection{AST Nodes}
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\declaremodule{}{compiler.ast}
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The \module{compiler.ast} module is generated from a text file that
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describes each node type and its elements. Each node type is
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represented as a class that inherits from the abstract base class
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\class{compiler.ast.Node} and defines a set of named attributes for
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child nodes.
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\begin{classdesc}{Node}{}
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|
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The \class{Node} instances are created automatically by the parser
|
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generator. The recommended interface for specific \class{Node}
|
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instances is to use the public attributes to access child nodes. A
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public attribute may be bound to a single node or to a sequence of
|
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nodes, depending on the \class{Node} type. For example, the
|
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\member{bases} attribute of the \class{Class} node, is bound to a
|
||||
list of base class nodes, and the \member{doc} attribute is bound to
|
||||
a single node.
|
||||
|
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Each \class{Node} instance has a \member{lineno} attribute which may
|
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be \code{None}. XXX Not sure what the rules are for which nodes
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will have a useful lineno.
|
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\end{classdesc}
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||||
|
||||
All \class{Node} objects offer the following methods:
|
||||
|
||||
\begin{methoddesc}{getChildren}{}
|
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Returns a flattened list of the child nodes and objects in the
|
||||
order they occur. Specifically, the order of the nodes is the
|
||||
order in which they appear in the Python grammar. Not all of the
|
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children are \class{Node} instances. The names of functions and
|
||||
classes, for example, are plain strings.
|
||||
\end{methoddesc}
|
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|
||||
\begin{methoddesc}{getChildNodes}{}
|
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Returns a flattened list of the child nodes in the order they
|
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occur. This method is like \method{getChildren()}, except that it
|
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only returns those children that are \class{Node} instances.
|
||||
\end{methoddesc}
|
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|
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Two examples illustrate the general structure of \class{Node}
|
||||
classes. The \keyword{while} statement is defined by the following
|
||||
grammar production:
|
||||
|
||||
\begin{verbatim}
|
||||
while_stmt: "while" expression ":" suite
|
||||
["else" ":" suite]
|
||||
\end{verbatim}
|
||||
|
||||
The \class{While} node has three attributes: \member{test},
|
||||
\member{body}, and \member{else_}. (If the natural name for an
|
||||
attribute is also a Python reserved word, it can't be used as an
|
||||
attribute name. An underscore is appended to the word to make it a
|
||||
legal identifier, hence \member{else_} instead of \keyword{else}.)
|
||||
|
||||
The \keyword{if} statement is more complicated because it can include
|
||||
several tests.
|
||||
|
||||
\begin{verbatim}
|
||||
if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
|
||||
\end{verbatim}
|
||||
|
||||
The \class{If} node only defines two attributes: \member{tests} and
|
||||
\member{else_}. The \member{tests} attribute is a sequence of test
|
||||
expression, consequent body pairs. There is one pair for each
|
||||
\keyword{if}/\keyword{elif} clause. The first element of the pair is
|
||||
the test expression. The second elements is a \class{Stmt} node that
|
||||
contains the code to execute if the test is true.
|
||||
|
||||
The \method{getChildren()} method of \class{If} returns a flat list of
|
||||
child nodes. If there are three \keyword{if}/\keyword{elif} clauses
|
||||
and no \keyword{else} clause, then \method{getChildren()} will return
|
||||
a list of six elements: the first test expression, the first
|
||||
\class{Stmt}, the second text expression, etc.
|
||||
|
||||
The following table lists each of the \class{Node} subclasses defined
|
||||
in \module{compiler.ast} and each of the public attributes available
|
||||
on their instances. The values of most of the attributes are
|
||||
themselves \class{Node} instances or sequences of instances. When the
|
||||
value is something other than an instance, the type is noted in the
|
||||
comment. The attributes are listed in the order in which they are
|
||||
returned by \method{getChildren()} and \method{getChildNodes()}.
|
||||
|
||||
\input{asttable}
|
||||
|
||||
|
||||
\subsection{Assignment nodes}
|
||||
|
||||
There is a collection of nodes used to represent assignments. Each
|
||||
assignment statement in the source code becomes a single
|
||||
\class{Assign} node in the AST. The \member{nodes} attribute is a
|
||||
list that contains a node for each assignment target. This is
|
||||
necessary because assignment can be chained, e.g. \code{a = b = 2}.
|
||||
Each \class{Node} in the list will be one of the following classes:
|
||||
\class{AssAttr}, \class{AssList}, \class{AssName}, or
|
||||
\class{AssTuple}.
|
||||
|
||||
Each target assignment node will describe the kind of object being
|
||||
assigned to: \class{AssName} for a simple name, e.g. \code{a = 1}.
|
||||
\class{AssAttr} for an attribute assigned, e.g. \code{a.x = 1}.
|
||||
\class{AssList} and \class{AssTuple} for list and tuple expansion
|
||||
respectively, e.g. \code{a, b, c = a_tuple}.
|
||||
|
||||
The target assignment nodes also have a \member{flags} attribute that
|
||||
indicates whether the node is being used for assignment or in a delete
|
||||
statement. The \class{AssName} is also used to represent a delete
|
||||
statement, e.g. \class{del x}.
|
||||
|
||||
When an expression contains several attribute references, an
|
||||
assignment or delete statement will contain only one \class{AssAttr}
|
||||
node -- for the final attribute reference. The other attribute
|
||||
references will be represented as \class{Getattr} nodes in the
|
||||
\member{expr} attribute of the \class{AssAttr} instance.
|
||||
|
||||
\subsection{Examples}
|
||||
|
||||
This section shows several simple examples of ASTs for Python source
|
||||
code. The examples demonstrate how to use the \function{parse()}
|
||||
function, what the repr of an AST looks like, and how to access
|
||||
attributes of an AST node.
|
||||
|
||||
The first module defines a single function. Assume it is stored in
|
||||
\file{/tmp/doublelib.py}.
|
||||
|
||||
\begin{verbatim}
|
||||
"""This is an example module.
|
||||
|
||||
This is the docstring.
|
||||
"""
|
||||
|
||||
def double(x):
|
||||
"Return twice the argument"
|
||||
return x * 2
|
||||
\end{verbatim}
|
||||
|
||||
In the interactive interpreter session below, I have reformatted the
|
||||
long AST reprs for readability. The AST reprs use unqualified class
|
||||
names. If you want to create an instance from a repr, you must import
|
||||
the class names from the \module{compiler.ast} module.
|
||||
|
||||
\begin{verbatim}
|
||||
>>> import compiler
|
||||
>>> mod = compiler.parseFile("/tmp/doublelib.py")
|
||||
>>> mod
|
||||
Module('This is an example module.\n\nThis is the docstring.\n',
|
||||
Stmt([Function('double', ['x'], [], 0, 'Return twice the argument',
|
||||
Stmt([Return(Mul((Name('x'), Const(2))))]))]))
|
||||
>>> from compiler.ast import *
|
||||
>>> Module('This is an example module.\n\nThis is the docstring.\n',
|
||||
... Stmt([Function('double', ['x'], [], 0, 'Return twice the argument',
|
||||
... Stmt([Return(Mul((Name('x'), Const(2))))]))]))
|
||||
Module('This is an example module.\n\nThis is the docstring.\n',
|
||||
Stmt([Function('double', ['x'], [], 0, 'Return twice the argument',
|
||||
Stmt([Return(Mul((Name('x'), Const(2))))]))]))
|
||||
>>> mod.doc
|
||||
'This is an example module.\n\nThis is the docstring.\n'
|
||||
>>> for node in mod.node.nodes:
|
||||
... print node
|
||||
...
|
||||
Function('double', ['x'], [], 0, 'Return twice the argument',
|
||||
Stmt([Return(Mul((Name('x'), Const(2))))]))
|
||||
>>> func = mod.node.nodes[0]
|
||||
>>> func.code
|
||||
Stmt([Return(Mul((Name('x'), Const(2))))])
|
||||
\end{verbatim}
|
||||
|
||||
\section{Using Visitors to Walk ASTs}
|
||||
|
||||
\declaremodule{}{compiler.visitor}
|
||||
|
||||
The visitor pattern is ... The \refmodule{compiler} package uses a
|
||||
variant on the visitor pattern that takes advantage of Python's
|
||||
introspection features to elminiate the need for much of the visitor's
|
||||
infrastructure.
|
||||
|
||||
The classes being visited do not need to be programmed to accept
|
||||
visitors. The visitor need only define visit methods for classes it
|
||||
is specifically interested in; a default visit method can handle the
|
||||
rest.
|
||||
|
||||
XXX The magic \method{visit()} method for visitors.
|
||||
|
||||
\begin{funcdesc}{walk}{tree, visitor\optional{, verbose}}
|
||||
\end{funcdesc}
|
||||
|
||||
\begin{classdesc}{ASTVisitor}{}
|
||||
|
||||
The \class{ASTVisitor} is responsible for walking over the tree in the
|
||||
correct order. A walk begins with a call to \method{preorder()}. For
|
||||
each node, it checks the \var{visitor} argument to \method{preorder()}
|
||||
for a method named `visitNodeType,' where NodeType is the name of the
|
||||
node's class, e.g. for a \class{While} node a \method{visitWhile()}
|
||||
would be called. If the method exists, it is called with the node as
|
||||
its first argument.
|
||||
|
||||
The visitor method for a particular node type can control how child
|
||||
nodes are visited during the walk. The \class{ASTVisitor} modifies
|
||||
the visitor argument by adding a visit method to the visitor; this
|
||||
method can be used to visit a particular child node. If no visitor is
|
||||
found for a particular node type, the \method{default()} method is
|
||||
called.
|
||||
\end{classdesc}
|
||||
|
||||
\class{ASTVisitor} objects have the following methods:
|
||||
|
||||
XXX describe extra arguments
|
||||
|
||||
\begin{methoddesc}{default}{node\optional{, \moreargs}}
|
||||
\end{methoddesc}
|
||||
|
||||
\begin{methoddesc}{dispatch}{node\optional{, \moreargs}}
|
||||
\end{methoddesc}
|
||||
|
||||
\begin{methoddesc}{preorder}{tree, visitor}
|
||||
\end{methoddesc}
|
||||
|
||||
|
||||
\section{Bytecode Generation}
|
||||
|
||||
The code generator is a visitor that emits bytecodes. Each visit method
|
||||
can call the \method{emit()} method to emit a new bytecode. The basic
|
||||
code generator is specialized for modules, classes, and functions. An
|
||||
assembler converts that emitted instructions to the low-level bytecode
|
||||
format. It handles things like generator of constant lists of code
|
||||
objects and calculation of jump offsets.
|
||||
|
||||
|
||||
\input{compiler.ind} % Index
|
||||
|
||||
\end{document}
|
||||
Loading…
Reference in New Issue