Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

19 files changed, 1399 insertions, 0 deletions

diff --git a/third_party/python/ply/example/BASIC/README b/third_party/python/ply/example/BASIC/README
new file mode 100644
index 0000000000..be24a3005e
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/README
@@ -0,0 +1,79 @@
+Inspired by a September 14, 2006 Salon article "Why Johnny Can't Code" by
+David Brin (http://www.salon.com/tech/feature/2006/09/14/basic/index.html),
+I thought that a fully working BASIC interpreter might be an interesting,
+if not questionable, PLY example.  Uh, okay, so maybe it's just a bad idea,
+but in any case, here it is.
+
+In this example, you'll find a rough implementation of 1964 Dartmouth BASIC
+as described in the manual at:
+
+   http://www.bitsavers.org/pdf/dartmouth/BASIC_Oct64.pdf
+
+See also:
+
+  http://en.wikipedia.org/wiki/Dartmouth_BASIC
+
+This dialect is downright primitive---there are no string variables
+and no facilities for interactive input. Moreover, subroutines and functions
+are brain-dead even more than they usually are for BASIC. Of course,
+the GOTO statement is provided.
+
+Nevertheless, there are a few interesting aspects of this example:
+
+  - It illustrates a fully working interpreter including lexing, parsing,
+    and interpretation of instructions.
+ 
+  - The parser shows how to catch and report various kinds of parsing
+    errors in a more graceful way.
+
+  - The example both parses files (supplied on command line) and
+    interactive input entered line by line.
+
+  - It shows how you might represent parsed information.  In this case,
+    each BASIC statement is encoded into a Python tuple containing the
+    statement type and parameters.  These tuples are then stored in
+    a dictionary indexed by program line numbers.
+
+  - Even though it's just BASIC, the parser contains more than 80
+    rules and 150 parsing states. Thus, it's a little more meaty than
+    the calculator example.
+
+To use the example, run it as follows:
+
+   % python basic.py hello.bas
+   HELLO WORLD
+   %
+
+or use it interactively:
+
+   % python basic.py
+   [BASIC] 10 PRINT "HELLO WORLD"
+   [BASIC] 20 END
+   [BASIC] RUN
+   HELLO WORLD
+   [BASIC]
+
+The following files are defined:
+
+   basic.py         - High level script that controls everything
+   basiclex.py      - BASIC tokenizer
+   basparse.py      - BASIC parser
+   basinterp.py     - BASIC interpreter that runs parsed programs.
+
+In addition, a number of sample BASIC programs (.bas suffix) are
+provided.  These were taken out of the Dartmouth manual.
+
+Disclaimer: I haven't spent a ton of time testing this and it's likely that
+I've skimped here and there on a few finer details (e.g., strictly enforcing
+variable naming rules).  However, the interpreter seems to be able to run
+the examples in the BASIC manual.
+
+Have fun!
+
+-Dave
+
+
+
+
+
+
diff --git a/third_party/python/ply/example/BASIC/basic.py b/third_party/python/ply/example/BASIC/basic.py
new file mode 100644
index 0000000000..70ac9e7c74
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/basic.py
@@ -0,0 +1,65 @@
+# An implementation of Dartmouth BASIC (1964)
+#
+
+import sys
+sys.path.insert(0, "../..")
+
+if sys.version_info[0] >= 3:
+    raw_input = input
+
+import basiclex
+import basparse
+import basinterp
+
+# If a filename has been specified, we try to run it.
+# If a runtime error occurs, we bail out and enter
+# interactive mode below
+if len(sys.argv) == 2:
+    data = open(sys.argv[1]).read()
+    prog = basparse.parse(data)
+    if not prog:
+        raise SystemExit
+    b = basinterp.BasicInterpreter(prog)
+    try:
+        b.run()
+        raise SystemExit
+    except RuntimeError:
+        pass
+
+else:
+    b = basinterp.BasicInterpreter({})
+
+# Interactive mode.  This incrementally adds/deletes statements
+# from the program stored in the BasicInterpreter object.  In
+# addition, special commands 'NEW','LIST',and 'RUN' are added.
+# Specifying a line number with no code deletes that line from
+# the program.
+
+while 1:
+    try:
+        line = raw_input("[BASIC] ")
+    except EOFError:
+        raise SystemExit
+    if not line:
+        continue
+    line += "\n"
+    prog = basparse.parse(line)
+    if not prog:
+        continue
+
+    keys = list(prog)
+    if keys[0] > 0:
+        b.add_statements(prog)
+    else:
+        stat = prog[keys[0]]
+        if stat[0] == 'RUN':
+            try:
+                b.run()
+            except RuntimeError:
+                pass
+        elif stat[0] == 'LIST':
+            b.list()
+        elif stat[0] == 'BLANK':
+            b.del_line(stat[1])
+        elif stat[0] == 'NEW':
+            b.new()
diff --git a/third_party/python/ply/example/BASIC/basiclex.py b/third_party/python/ply/example/BASIC/basiclex.py
new file mode 100644
index 0000000000..4151f4c34f
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/basiclex.py
@@ -0,0 +1,61 @@
+# An implementation of Dartmouth BASIC (1964)
+
+from ply import *
+
+keywords = (
+    'LET', 'READ', 'DATA', 'PRINT', 'GOTO', 'IF', 'THEN', 'FOR', 'NEXT', 'TO', 'STEP',
+    'END', 'STOP', 'DEF', 'GOSUB', 'DIM', 'REM', 'RETURN', 'RUN', 'LIST', 'NEW',
+)
+
+tokens = keywords + (
+    'EQUALS', 'PLUS', 'MINUS', 'TIMES', 'DIVIDE', 'POWER',
+    'LPAREN', 'RPAREN', 'LT', 'LE', 'GT', 'GE', 'NE',
+    'COMMA', 'SEMI', 'INTEGER', 'FLOAT', 'STRING',
+    'ID', 'NEWLINE'
+)
+
+t_ignore = ' \t'
+
+
+def t_REM(t):
+    r'REM .*'
+    return t
+
+
+def t_ID(t):
+    r'[A-Z][A-Z0-9]*'
+    if t.value in keywords:
+        t.type = t.value
+    return t
+
+t_EQUALS = r'='
+t_PLUS = r'\+'
+t_MINUS = r'-'
+t_TIMES = r'\*'
+t_POWER = r'\^'
+t_DIVIDE = r'/'
+t_LPAREN = r'\('
+t_RPAREN = r'\)'
+t_LT = r'<'
+t_LE = r'<='
+t_GT = r'>'
+t_GE = r'>='
+t_NE = r'<>'
+t_COMMA = r'\,'
+t_SEMI = r';'
+t_INTEGER = r'\d+'
+t_FLOAT = r'((\d*\.\d+)(E[\+-]?\d+)?|([1-9]\d*E[\+-]?\d+))'
+t_STRING = r'\".*?\"'
+
+
+def t_NEWLINE(t):
+    r'\n'
+    t.lexer.lineno += 1
+    return t
+
+
+def t_error(t):
+    print("Illegal character %s" % t.value[0])
+    t.lexer.skip(1)
+
+lex.lex(debug=0)
diff --git a/third_party/python/ply/example/BASIC/basiclog.py b/third_party/python/ply/example/BASIC/basiclog.py
new file mode 100644
index 0000000000..9dcc7feda6
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/basiclog.py
@@ -0,0 +1,73 @@
+# An implementation of Dartmouth BASIC (1964)
+#
+
+import sys
+sys.path.insert(0, "../..")
+
+if sys.version_info[0] >= 3:
+    raw_input = input
+
+import logging
+logging.basicConfig(
+    level=logging.INFO,
+    filename="parselog.txt",
+    filemode="w"
+)
+log = logging.getLogger()
+
+import basiclex
+import basparse
+import basinterp
+
+# If a filename has been specified, we try to run it.
+# If a runtime error occurs, we bail out and enter
+# interactive mode below
+if len(sys.argv) == 2:
+    data = open(sys.argv[1]).read()
+    prog = basparse.parse(data, debug=log)
+    if not prog:
+        raise SystemExit
+    b = basinterp.BasicInterpreter(prog)
+    try:
+        b.run()
+        raise SystemExit
+    except RuntimeError:
+        pass
+
+else:
+    b = basinterp.BasicInterpreter({})
+
+# Interactive mode.  This incrementally adds/deletes statements
+# from the program stored in the BasicInterpreter object.  In
+# addition, special commands 'NEW','LIST',and 'RUN' are added.
+# Specifying a line number with no code deletes that line from
+# the program.
+
+while 1:
+    try:
+        line = raw_input("[BASIC] ")
+    except EOFError:
+        raise SystemExit
+    if not line:
+        continue
+    line += "\n"
+    prog = basparse.parse(line, debug=log)
+    if not prog:
+        continue
+
+    keys = list(prog)
+    if keys[0] > 0:
+        b.add_statements(prog)
+    else:
+        stat = prog[keys[0]]
+        if stat[0] == 'RUN':
+            try:
+                b.run()
+            except RuntimeError:
+                pass
+        elif stat[0] == 'LIST':
+            b.list()
+        elif stat[0] == 'BLANK':
+            b.del_line(stat[1])
+        elif stat[0] == 'NEW':
+            b.new()
diff --git a/third_party/python/ply/example/BASIC/basinterp.py b/third_party/python/ply/example/BASIC/basinterp.py
new file mode 100644
index 0000000000..67762c797b
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/basinterp.py
@@ -0,0 +1,496 @@
+# This file provides the runtime support for running a basic program
+# Assumes the program has been parsed using basparse.py
+
+import sys
+import math
+import random
+
+
+class BasicInterpreter:
+
+    # Initialize the interpreter. prog is a dictionary
+    # containing (line,statement) mappings
+    def __init__(self, prog):
+        self.prog = prog
+
+        self.functions = {           # Built-in function table
+            'SIN': lambda z: math.sin(self.eval(z)),
+            'COS': lambda z: math.cos(self.eval(z)),
+            'TAN': lambda z: math.tan(self.eval(z)),
+            'ATN': lambda z: math.atan(self.eval(z)),
+            'EXP': lambda z: math.exp(self.eval(z)),
+            'ABS': lambda z: abs(self.eval(z)),
+            'LOG': lambda z: math.log(self.eval(z)),
+            'SQR': lambda z: math.sqrt(self.eval(z)),
+            'INT': lambda z: int(self.eval(z)),
+            'RND': lambda z: random.random()
+        }
+
+    # Collect all data statements
+    def collect_data(self):
+        self.data = []
+        for lineno in self.stat:
+            if self.prog[lineno][0] == 'DATA':
+                self.data = self.data + self.prog[lineno][1]
+        self.dc = 0                  # Initialize the data counter
+
+    # Check for end statements
+    def check_end(self):
+        has_end = 0
+        for lineno in self.stat:
+            if self.prog[lineno][0] == 'END' and not has_end:
+                has_end = lineno
+        if not has_end:
+            print("NO END INSTRUCTION")
+            self.error = 1
+            return
+        if has_end != lineno:
+            print("END IS NOT LAST")
+            self.error = 1
+
+    # Check loops
+    def check_loops(self):
+        for pc in range(len(self.stat)):
+            lineno = self.stat[pc]
+            if self.prog[lineno][0] == 'FOR':
+                forinst = self.prog[lineno]
+                loopvar = forinst[1]
+                for i in range(pc + 1, len(self.stat)):
+                    if self.prog[self.stat[i]][0] == 'NEXT':
+                        nextvar = self.prog[self.stat[i]][1]
+                        if nextvar != loopvar:
+                            continue
+                        self.loopend[pc] = i
+                        break
+                else:
+                    print("FOR WITHOUT NEXT AT LINE %s" % self.stat[pc])
+                    self.error = 1
+
+    # Evaluate an expression
+    def eval(self, expr):
+        etype = expr[0]
+        if etype == 'NUM':
+            return expr[1]
+        elif etype == 'GROUP':
+            return self.eval(expr[1])
+        elif etype == 'UNARY':
+            if expr[1] == '-':
+                return -self.eval(expr[2])
+        elif etype == 'BINOP':
+            if expr[1] == '+':
+                return self.eval(expr[2]) + self.eval(expr[3])
+            elif expr[1] == '-':
+                return self.eval(expr[2]) - self.eval(expr[3])
+            elif expr[1] == '*':
+                return self.eval(expr[2]) * self.eval(expr[3])
+            elif expr[1] == '/':
+                return float(self.eval(expr[2])) / self.eval(expr[3])
+            elif expr[1] == '^':
+                return abs(self.eval(expr[2]))**self.eval(expr[3])
+        elif etype == 'VAR':
+            var, dim1, dim2 = expr[1]
+            if not dim1 and not dim2:
+                if var in self.vars:
+                    return self.vars[var]
+                else:
+                    print("UNDEFINED VARIABLE %s AT LINE %s" %
+                          (var, self.stat[self.pc]))
+                    raise RuntimeError
+            # May be a list lookup or a function evaluation
+            if dim1 and not dim2:
+                if var in self.functions:
+                    # A function
+                    return self.functions[var](dim1)
+                else:
+                    # A list evaluation
+                    if var in self.lists:
+                        dim1val = self.eval(dim1)
+                        if dim1val < 1 or dim1val > len(self.lists[var]):
+                            print("LIST INDEX OUT OF BOUNDS AT LINE %s" %
+                                  self.stat[self.pc])
+                            raise RuntimeError
+                        return self.lists[var][dim1val - 1]
+            if dim1 and dim2:
+                if var in self.tables:
+                    dim1val = self.eval(dim1)
+                    dim2val = self.eval(dim2)
+                    if dim1val < 1 or dim1val > len(self.tables[var]) or dim2val < 1 or dim2val > len(self.tables[var][0]):
+                        print("TABLE INDEX OUT OUT BOUNDS AT LINE %s" %
+                              self.stat[self.pc])
+                        raise RuntimeError
+                    return self.tables[var][dim1val - 1][dim2val - 1]
+            print("UNDEFINED VARIABLE %s AT LINE %s" %
+                  (var, self.stat[self.pc]))
+            raise RuntimeError
+
+    # Evaluate a relational expression
+    def releval(self, expr):
+        etype = expr[1]
+        lhs = self.eval(expr[2])
+        rhs = self.eval(expr[3])
+        if etype == '<':
+            if lhs < rhs:
+                return 1
+            else:
+                return 0
+
+        elif etype == '<=':
+            if lhs <= rhs:
+                return 1
+            else:
+                return 0
+
+        elif etype == '>':
+            if lhs > rhs:
+                return 1
+            else:
+                return 0
+
+        elif etype == '>=':
+            if lhs >= rhs:
+                return 1
+            else:
+                return 0
+
+        elif etype == '=':
+            if lhs == rhs:
+                return 1
+            else:
+                return 0
+
+        elif etype == '<>':
+            if lhs != rhs:
+                return 1
+            else:
+                return 0
+
+    # Assignment
+    def assign(self, target, value):
+        var, dim1, dim2 = target
+        if not dim1 and not dim2:
+            self.vars[var] = self.eval(value)
+        elif dim1 and not dim2:
+            # List assignment
+            dim1val = self.eval(dim1)
+            if not var in self.lists:
+                self.lists[var] = [0] * 10
+
+            if dim1val > len(self.lists[var]):
+                print ("DIMENSION TOO LARGE AT LINE %s" % self.stat[self.pc])
+                raise RuntimeError
+            self.lists[var][dim1val - 1] = self.eval(value)
+        elif dim1 and dim2:
+            dim1val = self.eval(dim1)
+            dim2val = self.eval(dim2)
+            if not var in self.tables:
+                temp = [0] * 10
+                v = []
+                for i in range(10):
+                    v.append(temp[:])
+                self.tables[var] = v
+            # Variable already exists
+            if dim1val > len(self.tables[var]) or dim2val > len(self.tables[var][0]):
+                print("DIMENSION TOO LARGE AT LINE %s" % self.stat[self.pc])
+                raise RuntimeError
+            self.tables[var][dim1val - 1][dim2val - 1] = self.eval(value)
+
+    # Change the current line number
+    def goto(self, linenum):
+        if not linenum in self.prog:
+            print("UNDEFINED LINE NUMBER %d AT LINE %d" %
+                  (linenum, self.stat[self.pc]))
+            raise RuntimeError
+        self.pc = self.stat.index(linenum)
+
+    # Run it
+    def run(self):
+        self.vars = {}            # All variables
+        self.lists = {}            # List variables
+        self.tables = {}            # Tables
+        self.loops = []            # Currently active loops
+        self.loopend = {}            # Mapping saying where loops end
+        self.gosub = None           # Gosub return point (if any)
+        self.error = 0              # Indicates program error
+
+        self.stat = list(self.prog)  # Ordered list of all line numbers
+        self.stat.sort()
+        self.pc = 0                  # Current program counter
+
+        # Processing prior to running
+
+        self.collect_data()          # Collect all of the data statements
+        self.check_end()
+        self.check_loops()
+
+        if self.error:
+            raise RuntimeError
+
+        while 1:
+            line = self.stat[self.pc]
+            instr = self.prog[line]
+
+            op = instr[0]
+
+            # END and STOP statements
+            if op == 'END' or op == 'STOP':
+                break           # We're done
+
+            # GOTO statement
+            elif op == 'GOTO':
+                newline = instr[1]
+                self.goto(newline)
+                continue
+
+            # PRINT statement
+            elif op == 'PRINT':
+                plist = instr[1]
+                out = ""
+                for label, val in plist:
+                    if out:
+                        out += ' ' * (15 - (len(out) % 15))
+                    out += label
+                    if val:
+                        if label:
+                            out += " "
+                        eval = self.eval(val)
+                        out += str(eval)
+                sys.stdout.write(out)
+                end = instr[2]
+                if not (end == ',' or end == ';'):
+                    sys.stdout.write("\n")
+                if end == ',':
+                    sys.stdout.write(" " * (15 - (len(out) % 15)))
+                if end == ';':
+                    sys.stdout.write(" " * (3 - (len(out) % 3)))
+
+            # LET statement
+            elif op == 'LET':
+                target = instr[1]
+                value = instr[2]
+                self.assign(target, value)
+
+            # READ statement
+            elif op == 'READ':
+                for target in instr[1]:
+                    if self.dc < len(self.data):
+                        value = ('NUM', self.data[self.dc])
+                        self.assign(target, value)
+                        self.dc += 1
+                    else:
+                        # No more data.  Program ends
+                        return
+            elif op == 'IF':
+                relop = instr[1]
+                newline = instr[2]
+                if (self.releval(relop)):
+                    self.goto(newline)
+                    continue
+
+            elif op == 'FOR':
+                loopvar = instr[1]
+                initval = instr[2]
+                finval = instr[3]
+                stepval = instr[4]
+
+                # Check to see if this is a new loop
+                if not self.loops or self.loops[-1][0] != self.pc:
+                    # Looks like a new loop. Make the initial assignment
+                    newvalue = initval
+                    self.assign((loopvar, None, None), initval)
+                    if not stepval:
+                        stepval = ('NUM', 1)
+                    stepval = self.eval(stepval)    # Evaluate step here
+                    self.loops.append((self.pc, stepval))
+                else:
+                    # It's a repeat of the previous loop
+                    # Update the value of the loop variable according to the
+                    # step
+                    stepval = ('NUM', self.loops[-1][1])
+                    newvalue = (
+                        'BINOP', '+', ('VAR', (loopvar, None, None)), stepval)
+
+                if self.loops[-1][1] < 0:
+                    relop = '>='
+                else:
+                    relop = '<='
+                if not self.releval(('RELOP', relop, newvalue, finval)):
+                    # Loop is done. Jump to the NEXT
+                    self.pc = self.loopend[self.pc]
+                    self.loops.pop()
+                else:
+                    self.assign((loopvar, None, None), newvalue)
+
+            elif op == 'NEXT':
+                if not self.loops:
+                    print("NEXT WITHOUT FOR AT LINE %s" % line)
+                    return
+
+                nextvar = instr[1]
+                self.pc = self.loops[-1][0]
+                loopinst = self.prog[self.stat[self.pc]]
+                forvar = loopinst[1]
+                if nextvar != forvar:
+                    print("NEXT DOESN'T MATCH FOR AT LINE %s" % line)
+                    return
+                continue
+            elif op == 'GOSUB':
+                newline = instr[1]
+                if self.gosub:
+                    print("ALREADY IN A SUBROUTINE AT LINE %s" % line)
+                    return
+                self.gosub = self.stat[self.pc]
+                self.goto(newline)
+                continue
+
+            elif op == 'RETURN':
+                if not self.gosub:
+                    print("RETURN WITHOUT A GOSUB AT LINE %s" % line)
+                    return
+                self.goto(self.gosub)
+                self.gosub = None
+
+            elif op == 'FUNC':
+                fname = instr[1]
+                pname = instr[2]
+                expr = instr[3]
+
+                def eval_func(pvalue, name=pname, self=self, expr=expr):
+                    self.assign((pname, None, None), pvalue)
+                    return self.eval(expr)
+                self.functions[fname] = eval_func
+
+            elif op == 'DIM':
+                for vname, x, y in instr[1]:
+                    if y == 0:
+                        # Single dimension variable
+                        self.lists[vname] = [0] * x
+                    else:
+                        # Double dimension variable
+                        temp = [0] * y
+                        v = []
+                        for i in range(x):
+                            v.append(temp[:])
+                        self.tables[vname] = v
+
+            self.pc += 1
+
+    # Utility functions for program listing
+    def expr_str(self, expr):
+        etype = expr[0]
+        if etype == 'NUM':
+            return str(expr[1])
+        elif etype == 'GROUP':
+            return "(%s)" % self.expr_str(expr[1])
+        elif etype == 'UNARY':
+            if expr[1] == '-':
+                return "-" + str(expr[2])
+        elif etype == 'BINOP':
+            return "%s %s %s" % (self.expr_str(expr[2]), expr[1], self.expr_str(expr[3]))
+        elif etype == 'VAR':
+            return self.var_str(expr[1])
+
+    def relexpr_str(self, expr):
+        return "%s %s %s" % (self.expr_str(expr[2]), expr[1], self.expr_str(expr[3]))
+
+    def var_str(self, var):
+        varname, dim1, dim2 = var
+        if not dim1 and not dim2:
+            return varname
+        if dim1 and not dim2:
+            return "%s(%s)" % (varname, self.expr_str(dim1))
+        return "%s(%s,%s)" % (varname, self.expr_str(dim1), self.expr_str(dim2))
+
+    # Create a program listing
+    def list(self):
+        stat = list(self.prog)      # Ordered list of all line numbers
+        stat.sort()
+        for line in stat:
+            instr = self.prog[line]
+            op = instr[0]
+            if op in ['END', 'STOP', 'RETURN']:
+                print("%s %s" % (line, op))
+                continue
+            elif op == 'REM':
+                print("%s %s" % (line, instr[1]))
+            elif op == 'PRINT':
+                _out = "%s %s " % (line, op)
+                first = 1
+                for p in instr[1]:
+                    if not first:
+                        _out += ", "
+                    if p[0] and p[1]:
+                        _out += '"%s"%s' % (p[0], self.expr_str(p[1]))
+                    elif p[1]:
+                        _out += self.expr_str(p[1])
+                    else:
+                        _out += '"%s"' % (p[0],)
+                    first = 0
+                if instr[2]:
+                    _out += instr[2]
+                print(_out)
+            elif op == 'LET':
+                print("%s LET %s = %s" %
+                      (line, self.var_str(instr[1]), self.expr_str(instr[2])))
+            elif op == 'READ':
+                _out = "%s READ " % line
+                first = 1
+                for r in instr[1]:
+                    if not first:
+                        _out += ","
+                    _out += self.var_str(r)
+                    first = 0
+                print(_out)
+            elif op == 'IF':
+                print("%s IF %s THEN %d" %
+                      (line, self.relexpr_str(instr[1]), instr[2]))
+            elif op == 'GOTO' or op == 'GOSUB':
+                print("%s %s %s" % (line, op, instr[1]))
+            elif op == 'FOR':
+                _out = "%s FOR %s = %s TO %s" % (
+                    line, instr[1], self.expr_str(instr[2]), self.expr_str(instr[3]))
+                if instr[4]:
+                    _out += " STEP %s" % (self.expr_str(instr[4]))
+                print(_out)
+            elif op == 'NEXT':
+                print("%s NEXT %s" % (line, instr[1]))
+            elif op == 'FUNC':
+                print("%s DEF %s(%s) = %s" %
+                      (line, instr[1], instr[2], self.expr_str(instr[3])))
+            elif op == 'DIM':
+                _out = "%s DIM " % line
+                first = 1
+                for vname, x, y in instr[1]:
+                    if not first:
+                        _out += ","
+                    first = 0
+                    if y == 0:
+                        _out += "%s(%d)" % (vname, x)
+                    else:
+                        _out += "%s(%d,%d)" % (vname, x, y)
+
+                print(_out)
+            elif op == 'DATA':
+                _out = "%s DATA " % line
+                first = 1
+                for v in instr[1]:
+                    if not first:
+                        _out += ","
+                    first = 0
+                    _out += v
+                print(_out)
+
+    # Erase the current program
+    def new(self):
+        self.prog = {}
+
+    # Insert statements
+    def add_statements(self, prog):
+        for line, stat in prog.items():
+            self.prog[line] = stat
+
+    # Delete a statement
+    def del_line(self, lineno):
+        try:
+            del self.prog[lineno]
+        except KeyError:
+            pass
diff --git a/third_party/python/ply/example/BASIC/basparse.py b/third_party/python/ply/example/BASIC/basparse.py
new file mode 100644
index 0000000000..d610c7d909
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/basparse.py
@@ -0,0 +1,474 @@
+# An implementation of Dartmouth BASIC (1964)
+#
+
+from ply import *
+import basiclex
+
+tokens = basiclex.tokens
+
+precedence = (
+    ('left', 'PLUS', 'MINUS'),
+    ('left', 'TIMES', 'DIVIDE'),
+    ('left', 'POWER'),
+    ('right', 'UMINUS')
+)
+
+# A BASIC program is a series of statements.  We represent the program as a
+# dictionary of tuples indexed by line number.
+
+
+def p_program(p):
+    '''program : program statement
+               | statement'''
+
+    if len(p) == 2 and p[1]:
+        p[0] = {}
+        line, stat = p[1]
+        p[0][line] = stat
+    elif len(p) == 3:
+        p[0] = p[1]
+        if not p[0]:
+            p[0] = {}
+        if p[2]:
+            line, stat = p[2]
+            p[0][line] = stat
+
+# This catch-all rule is used for any catastrophic errors.  In this case,
+# we simply return nothing
+
+
+def p_program_error(p):
+    '''program : error'''
+    p[0] = None
+    p.parser.error = 1
+
+# Format of all BASIC statements.
+
+
+def p_statement(p):
+    '''statement : INTEGER command NEWLINE'''
+    if isinstance(p[2], str):
+        print("%s %s %s" % (p[2], "AT LINE", p[1]))
+        p[0] = None
+        p.parser.error = 1
+    else:
+        lineno = int(p[1])
+        p[0] = (lineno, p[2])
+
+# Interactive statements.
+
+
+def p_statement_interactive(p):
+    '''statement : RUN NEWLINE
+                 | LIST NEWLINE
+                 | NEW NEWLINE'''
+    p[0] = (0, (p[1], 0))
+
+# Blank line number
+
+
+def p_statement_blank(p):
+    '''statement : INTEGER NEWLINE'''
+    p[0] = (0, ('BLANK', int(p[1])))
+
+# Error handling for malformed statements
+
+
+def p_statement_bad(p):
+    '''statement : INTEGER error NEWLINE'''
+    print("MALFORMED STATEMENT AT LINE %s" % p[1])
+    p[0] = None
+    p.parser.error = 1
+
+# Blank line
+
+
+def p_statement_newline(p):
+    '''statement : NEWLINE'''
+    p[0] = None
+
+# LET statement
+
+
+def p_command_let(p):
+    '''command : LET variable EQUALS expr'''
+    p[0] = ('LET', p[2], p[4])
+
+
+def p_command_let_bad(p):
+    '''command : LET variable EQUALS error'''
+    p[0] = "BAD EXPRESSION IN LET"
+
+# READ statement
+
+
+def p_command_read(p):
+    '''command : READ varlist'''
+    p[0] = ('READ', p[2])
+
+
+def p_command_read_bad(p):
+    '''command : READ error'''
+    p[0] = "MALFORMED VARIABLE LIST IN READ"
+
+# DATA statement
+
+
+def p_command_data(p):
+    '''command : DATA numlist'''
+    p[0] = ('DATA', p[2])
+
+
+def p_command_data_bad(p):
+    '''command : DATA error'''
+    p[0] = "MALFORMED NUMBER LIST IN DATA"
+
+# PRINT statement
+
+
+def p_command_print(p):
+    '''command : PRINT plist optend'''
+    p[0] = ('PRINT', p[2], p[3])
+
+
+def p_command_print_bad(p):
+    '''command : PRINT error'''
+    p[0] = "MALFORMED PRINT STATEMENT"
+
+# Optional ending on PRINT. Either a comma (,) or semicolon (;)
+
+
+def p_optend(p):
+    '''optend : COMMA 
+              | SEMI
+              |'''
+    if len(p) == 2:
+        p[0] = p[1]
+    else:
+        p[0] = None
+
+# PRINT statement with no arguments
+
+
+def p_command_print_empty(p):
+    '''command : PRINT'''
+    p[0] = ('PRINT', [], None)
+
+# GOTO statement
+
+
+def p_command_goto(p):
+    '''command : GOTO INTEGER'''
+    p[0] = ('GOTO', int(p[2]))
+
+
+def p_command_goto_bad(p):
+    '''command : GOTO error'''
+    p[0] = "INVALID LINE NUMBER IN GOTO"
+
+# IF-THEN statement
+
+
+def p_command_if(p):
+    '''command : IF relexpr THEN INTEGER'''
+    p[0] = ('IF', p[2], int(p[4]))
+
+
+def p_command_if_bad(p):
+    '''command : IF error THEN INTEGER'''
+    p[0] = "BAD RELATIONAL EXPRESSION"
+
+
+def p_command_if_bad2(p):
+    '''command : IF relexpr THEN error'''
+    p[0] = "INVALID LINE NUMBER IN THEN"
+
+# FOR statement
+
+
+def p_command_for(p):
+    '''command : FOR ID EQUALS expr TO expr optstep'''
+    p[0] = ('FOR', p[2], p[4], p[6], p[7])
+
+
+def p_command_for_bad_initial(p):
+    '''command : FOR ID EQUALS error TO expr optstep'''
+    p[0] = "BAD INITIAL VALUE IN FOR STATEMENT"
+
+
+def p_command_for_bad_final(p):
+    '''command : FOR ID EQUALS expr TO error optstep'''
+    p[0] = "BAD FINAL VALUE IN FOR STATEMENT"
+
+
+def p_command_for_bad_step(p):
+    '''command : FOR ID EQUALS expr TO expr STEP error'''
+    p[0] = "MALFORMED STEP IN FOR STATEMENT"
+
+# Optional STEP qualifier on FOR statement
+
+
+def p_optstep(p):
+    '''optstep : STEP expr
+               | empty'''
+    if len(p) == 3:
+        p[0] = p[2]
+    else:
+        p[0] = None
+
+# NEXT statement
+
+
+def p_command_next(p):
+    '''command : NEXT ID'''
+
+    p[0] = ('NEXT', p[2])
+
+
+def p_command_next_bad(p):
+    '''command : NEXT error'''
+    p[0] = "MALFORMED NEXT"
+
+# END statement
+
+
+def p_command_end(p):
+    '''command : END'''
+    p[0] = ('END',)
+
+# REM statement
+
+
+def p_command_rem(p):
+    '''command : REM'''
+    p[0] = ('REM', p[1])
+
+# STOP statement
+
+
+def p_command_stop(p):
+    '''command : STOP'''
+    p[0] = ('STOP',)
+
+# DEF statement
+
+
+def p_command_def(p):
+    '''command : DEF ID LPAREN ID RPAREN EQUALS expr'''
+    p[0] = ('FUNC', p[2], p[4], p[7])
+
+
+def p_command_def_bad_rhs(p):
+    '''command : DEF ID LPAREN ID RPAREN EQUALS error'''
+    p[0] = "BAD EXPRESSION IN DEF STATEMENT"
+
+
+def p_command_def_bad_arg(p):
+    '''command : DEF ID LPAREN error RPAREN EQUALS expr'''
+    p[0] = "BAD ARGUMENT IN DEF STATEMENT"
+
+# GOSUB statement
+
+
+def p_command_gosub(p):
+    '''command : GOSUB INTEGER'''
+    p[0] = ('GOSUB', int(p[2]))
+
+
+def p_command_gosub_bad(p):
+    '''command : GOSUB error'''
+    p[0] = "INVALID LINE NUMBER IN GOSUB"
+
+# RETURN statement
+
+
+def p_command_return(p):
+    '''command : RETURN'''
+    p[0] = ('RETURN',)
+
+# DIM statement
+
+
+def p_command_dim(p):
+    '''command : DIM dimlist'''
+    p[0] = ('DIM', p[2])
+
+
+def p_command_dim_bad(p):
+    '''command : DIM error'''
+    p[0] = "MALFORMED VARIABLE LIST IN DIM"
+
+# List of variables supplied to DIM statement
+
+
+def p_dimlist(p):
+    '''dimlist : dimlist COMMA dimitem
+               | dimitem'''
+    if len(p) == 4:
+        p[0] = p[1]
+        p[0].append(p[3])
+    else:
+        p[0] = [p[1]]
+
+# DIM items
+
+
+def p_dimitem_single(p):
+    '''dimitem : ID LPAREN INTEGER RPAREN'''
+    p[0] = (p[1], eval(p[3]), 0)
+
+
+def p_dimitem_double(p):
+    '''dimitem : ID LPAREN INTEGER COMMA INTEGER RPAREN'''
+    p[0] = (p[1], eval(p[3]), eval(p[5]))
+
+# Arithmetic expressions
+
+
+def p_expr_binary(p):
+    '''expr : expr PLUS expr
+            | expr MINUS expr
+            | expr TIMES expr
+            | expr DIVIDE expr
+            | expr POWER expr'''
+
+    p[0] = ('BINOP', p[2], p[1], p[3])
+
+
+def p_expr_number(p):
+    '''expr : INTEGER
+            | FLOAT'''
+    p[0] = ('NUM', eval(p[1]))
+
+
+def p_expr_variable(p):
+    '''expr : variable'''
+    p[0] = ('VAR', p[1])
+
+
+def p_expr_group(p):
+    '''expr : LPAREN expr RPAREN'''
+    p[0] = ('GROUP', p[2])
+
+
+def p_expr_unary(p):
+    '''expr : MINUS expr %prec UMINUS'''
+    p[0] = ('UNARY', '-', p[2])
+
+# Relational expressions
+
+
+def p_relexpr(p):
+    '''relexpr : expr LT expr
+               | expr LE expr
+               | expr GT expr
+               | expr GE expr
+               | expr EQUALS expr
+               | expr NE expr'''
+    p[0] = ('RELOP', p[2], p[1], p[3])
+
+# Variables
+
+
+def p_variable(p):
+    '''variable : ID
+              | ID LPAREN expr RPAREN
+              | ID LPAREN expr COMMA expr RPAREN'''
+    if len(p) == 2:
+        p[0] = (p[1], None, None)
+    elif len(p) == 5:
+        p[0] = (p[1], p[3], None)
+    else:
+        p[0] = (p[1], p[3], p[5])
+
+# Builds a list of variable targets as a Python list
+
+
+def p_varlist(p):
+    '''varlist : varlist COMMA variable
+               | variable'''
+    if len(p) > 2:
+        p[0] = p[1]
+        p[0].append(p[3])
+    else:
+        p[0] = [p[1]]
+
+
+# Builds a list of numbers as a Python list
+
+def p_numlist(p):
+    '''numlist : numlist COMMA number
+               | number'''
+
+    if len(p) > 2:
+        p[0] = p[1]
+        p[0].append(p[3])
+    else:
+        p[0] = [p[1]]
+
+# A number. May be an integer or a float
+
+
+def p_number(p):
+    '''number  : INTEGER
+               | FLOAT'''
+    p[0] = eval(p[1])
+
+# A signed number.
+
+
+def p_number_signed(p):
+    '''number  : MINUS INTEGER
+               | MINUS FLOAT'''
+    p[0] = eval("-" + p[2])
+
+# List of targets for a print statement
+# Returns a list of tuples (label,expr)
+
+
+def p_plist(p):
+    '''plist   : plist COMMA pitem
+               | pitem'''
+    if len(p) > 3:
+        p[0] = p[1]
+        p[0].append(p[3])
+    else:
+        p[0] = [p[1]]
+
+
+def p_item_string(p):
+    '''pitem : STRING'''
+    p[0] = (p[1][1:-1], None)
+
+
+def p_item_string_expr(p):
+    '''pitem : STRING expr'''
+    p[0] = (p[1][1:-1], p[2])
+
+
+def p_item_expr(p):
+    '''pitem : expr'''
+    p[0] = ("", p[1])
+
+# Empty
+
+
+def p_empty(p):
+    '''empty : '''
+
+# Catastrophic error handler
+
+
+def p_error(p):
+    if not p:
+        print("SYNTAX ERROR AT EOF")
+
+bparser = yacc.yacc()
+
+
+def parse(data, debug=0):
+    bparser.error = 0
+    p = bparser.parse(data, debug=debug)
+    if bparser.error:
+        return None
+    return p
diff --git a/third_party/python/ply/example/BASIC/dim.bas b/third_party/python/ply/example/BASIC/dim.bas
new file mode 100644
index 0000000000..87bd95b32e
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/dim.bas
@@ -0,0 +1,14 @@
+5 DIM A(50,15)
+10 FOR I = 1 TO 50
+20 FOR J = 1 TO 15
+30   LET A(I,J) = I + J
+35 REM  PRINT I,J, A(I,J)
+40 NEXT J
+50 NEXT I
+100 FOR I = 1 TO 50
+110 FOR J = 1 TO 15
+120   PRINT A(I,J),
+130 NEXT J
+140 PRINT 
+150 NEXT I
+999 END
diff --git a/third_party/python/ply/example/BASIC/func.bas b/third_party/python/ply/example/BASIC/func.bas
new file mode 100644
index 0000000000..447ee16a92
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/func.bas
@@ -0,0 +1,5 @@
+10 DEF FDX(X) = 2*X
+20 FOR I = 0 TO 100
+30 PRINT FDX(I)
+40 NEXT I
+50 END
diff --git a/third_party/python/ply/example/BASIC/gcd.bas b/third_party/python/ply/example/BASIC/gcd.bas
new file mode 100644
index 0000000000..d0b7746089
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/gcd.bas
@@ -0,0 +1,22 @@
+10 PRINT "A","B","C","GCD"
+20 READ A,B,C
+30 LET X = A
+40 LET Y = B
+50 GOSUB 200
+60 LET X = G
+70 LET Y = C
+80 GOSUB 200
+90 PRINT A, B, C, G
+100 GOTO 20
+110 DATA 60, 90, 120
+120 DATA 38456, 64872, 98765
+130 DATA 32, 384, 72
+200 LET Q = INT(X/Y)
+210 LET R = X - Q*Y
+220 IF R = 0 THEN 300
+230 LET X = Y
+240 LET Y = R
+250 GOTO 200
+300 LET G = Y
+310 RETURN
+999 END
diff --git a/third_party/python/ply/example/BASIC/gosub.bas b/third_party/python/ply/example/BASIC/gosub.bas
new file mode 100644
index 0000000000..99737b16f1
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/gosub.bas
@@ -0,0 +1,13 @@
+100 LET X = 3
+110 GOSUB 400
+120 PRINT U, V, W
+200 LET X = 5
+210 GOSUB 400
+220 LET Z = U + 2*V + 3*W
+230 PRINT Z
+240 GOTO 999
+400 LET U = X*X
+410 LET V = X*X*X
+420 LET W = X*X*X*X + X*X*X + X*X + X
+430 RETURN
+999 END
diff --git a/third_party/python/ply/example/BASIC/hello.bas b/third_party/python/ply/example/BASIC/hello.bas
new file mode 100644
index 0000000000..cc6f0b0b51
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/hello.bas
@@ -0,0 +1,4 @@
+5  REM HELLO WORLD PROGAM
+10 PRINT "HELLO WORLD"
+99 END
+
diff --git a/third_party/python/ply/example/BASIC/linear.bas b/third_party/python/ply/example/BASIC/linear.bas
new file mode 100644
index 0000000000..56c08220b3
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/linear.bas
@@ -0,0 +1,17 @@
+1  REM ::: SOLVE A SYSTEM OF LINEAR EQUATIONS
+2  REM ::: A1*X1 + A2*X2 = B1
+3  REM ::: A3*X1 + A4*X2 = B2
+4  REM --------------------------------------
+10 READ A1, A2, A3, A4
+15 LET D = A1 * A4 - A3 * A2
+20 IF D = 0 THEN 65
+30 READ B1, B2
+37 LET X1 = (B1*A4 - B2*A2) / D
+42 LET X2 = (A1*B2 - A3*B1) / D
+55 PRINT X1, X2
+60 GOTO 30
+65 PRINT "NO UNIQUE SOLUTION"
+70 DATA 1, 2, 4
+80 DATA 2, -7, 5
+85 DATA 1, 3, 4, -7
+90 END
diff --git a/third_party/python/ply/example/BASIC/maxsin.bas b/third_party/python/ply/example/BASIC/maxsin.bas
new file mode 100644
index 0000000000..b96901530c
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/maxsin.bas
@@ -0,0 +1,12 @@
+5 PRINT "X VALUE", "SINE", "RESOLUTION"
+10 READ D
+20 LET M = -1
+30 FOR X = 0 TO 3 STEP D
+40 IF SIN(X) <= M THEN 80
+50 LET X0 = X
+60 LET M = SIN(X)
+80 NEXT X
+85 PRINT X0, M, D
+90 GOTO 10
+100 DATA .1, .01, .001
+110 END
diff --git a/third_party/python/ply/example/BASIC/powers.bas b/third_party/python/ply/example/BASIC/powers.bas
new file mode 100644
index 0000000000..a454dc3e21
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/powers.bas
@@ -0,0 +1,13 @@
+5 PRINT "THIS PROGRAM COMPUTES AND PRINTS THE NTH POWERS"
+6 PRINT "OF THE NUMBERS LESS THAN OR EQUAL TO N FOR VARIOUS"
+7 PRINT "N FROM 1 THROUGH 7"
+8 PRINT
+10 FOR N = 1 TO 7
+15 PRINT "N = "N
+20 FOR I = 1 TO N
+30 PRINT I^N,
+40 NEXT I
+50 PRINT
+60 PRINT
+70 NEXT N
+80 END
diff --git a/third_party/python/ply/example/BASIC/rand.bas b/third_party/python/ply/example/BASIC/rand.bas
new file mode 100644
index 0000000000..4ff7a14670
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/rand.bas
@@ -0,0 +1,4 @@
+10 FOR I = 1 TO 20
+20 PRINT INT(10*RND(0))
+30 NEXT I
+40 END
diff --git a/third_party/python/ply/example/BASIC/sales.bas b/third_party/python/ply/example/BASIC/sales.bas
new file mode 100644
index 0000000000..a39aefb762
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/sales.bas
@@ -0,0 +1,20 @@
+10 FOR I = 1 TO 3
+20 READ P(I)
+30 NEXT I
+40 FOR I = 1 TO 3
+50 FOR J = 1 TO 5
+60 READ S(I,J)
+70 NEXT J
+80 NEXT I
+90 FOR J = 1 TO 5
+100 LET S = 0
+110 FOR I = 1 TO 3
+120 LET S = S + P(I) * S(I,J)
+130 NEXT I
+140 PRINT "TOTAL SALES FOR SALESMAN"J, "$"S
+150 NEXT J
+200 DATA 1.25, 4.30, 2.50
+210 DATA 40, 20, 37, 29, 42
+220 DATA 10, 16, 3, 21, 8
+230 DATA 35, 47, 29, 16, 33
+300 END
diff --git a/third_party/python/ply/example/BASIC/sears.bas b/third_party/python/ply/example/BASIC/sears.bas
new file mode 100644
index 0000000000..5ced3974e2
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/sears.bas
@@ -0,0 +1,18 @@
+1 REM :: THIS PROGRAM COMPUTES HOW MANY TIMES YOU HAVE TO FOLD
+2 REM :: A PIECE OF PAPER SO THAT IT IS TALLER THAN THE
+3 REM :: SEARS TOWER.
+4 REM ::       S = HEIGHT OF TOWER (METERS)
+5 REM ::       T = THICKNESS OF PAPER (MILLIMETERS)
+10 LET S = 442
+20 LET T = 0.1
+30 REM CONVERT T TO METERS
+40 LET T = T * .001
+50 LET F = 1
+60 LET H = T
+100 IF H > S THEN 200
+120 LET H = 2 * H
+125 LET F = F + 1
+130 GOTO 100
+200 PRINT "NUMBER OF FOLDS ="F
+220 PRINT "FINAL HEIGHT    ="H
+999 END
diff --git a/third_party/python/ply/example/BASIC/sqrt1.bas b/third_party/python/ply/example/BASIC/sqrt1.bas
new file mode 100644
index 0000000000..6673a91524
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/sqrt1.bas
@@ -0,0 +1,5 @@
+10 LET X = 0
+20 LET X = X + 1
+30 PRINT X, SQR(X)
+40 IF X < 100 THEN 20
+50 END
diff --git a/third_party/python/ply/example/BASIC/sqrt2.bas b/third_party/python/ply/example/BASIC/sqrt2.bas
new file mode 100644
index 0000000000..862d85ef26
--- /dev/null
+++ b/third_party/python/ply/example/BASIC/sqrt2.bas
@@ -0,0 +1,4 @@
+10 FOR X = 1 TO 100
+20 PRINT X, SQR(X)
+30 NEXT X
+40 END