Compiler/Preprocessor
< Compiler
This task modifies the source code prior to the lexical analysis similar to the C built-in preprocessor. All design decisions go with as simple an example as possible to show concept and match the simple language the other tasks support.
Compiler/Preprocessor is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Create a preprocessor for the simple programming language specified in the lexical analysis task referenced below. The program should read input from a file and/or stdin, and write output to a file and/or stdout.
The program should treat any line starting with a hashtag (#) as a command to process. There are currently two valid commands, include and define. No space between the hashtag and its command. Multiple whitespace is treated the same as one.
The include command must be followed by whitespace and a double quoted string whose contents is the actual file to read. Includes should allow the inclusion of other files to a recursive limit of five active header files plus the original source file.
The define command must be followed by whitespace and a new macro name. Redefinition or overloading of the macro name is illegal. The same character convention for naming variables in the language is used for macro names. No whitespace is required in the arguments but is allowed between every token. When there are no parameters, both the definition or usage must either have an empty argument list or there must not be one. The empty list is required to avoid confusion when the definition needs parenthesizes to force precedence. If there is a close parenthesis, the whitespace trailing it is optional. Otherwise, it is required. From that point to end of line is the definition, whitespace removed from both the start and end of it. Whitespace within the definition between tokens must be maintained. Any names within the definition are treated as macro names first before it is assumed they are a variable in the language during the usage.
To make it easier to find, the usage will be within hashtags, and replaces its usage elsewhere in the files processed. These usages will be processed everywhere they are encountered without regard to the syntax of the sample language. The calling arguments replace the define's parameters as a simple string substitution. You may not assume the usage proceeds in an order to form complex combinations. Tokens detected during definition processing can remain separated during usage processing. If the contents within the double hashtags is not a valid macro usage, its entire text is written to the output as if it was not detected. It is not required to use the ending hashtag as the start of another macro usage. Both start and end hashtags must be on the same line.
There are three possible [optional] command line arguments, debug, input, and output. Debug is an implementer depended switch such as -d or --debug to allow the user to pick between the commands vanishing from the output or the commands appearing as comments in the output. Debug can be specified in any order on the command line beyond the command. Input is the file to process, when missing the console input is used. The Input is always specified before the Output. Output is the file to create, when missing the console output is used. If only one file is specified, it is the input file. If you wish to use an output file and console input, you must specify both arguments, who's usage is left up to the implementer. It is not required that there be a way to specify the console on the command line so you could use a file for the output and console for the input.
Input Specification
This is an example usage of this concept, given a header and source the output should be able to feed straight into the lexical analyzer task.
~~ Header.h ~~ #define area(h, w) h * w ~~ Source.t ~~ #include "Header.h" #define width 5 #define height 6 area = #area(height, width)#;
Output Specification
If you do not support a runtime debugging flag, your code should support only the second version. Otherwise, it should provide either. Yielding code output of:
area = 6 * 5;
Or:
/* Include Header.h */ /* Define area(h, w) as h * w */ /* End Header.h */ /* Define width as 5 */ /* Define height as 6 */ /* Use area, height, and width */ area = 6 * 5;
- Related Tasks
- Lexical Analyzer task
- Syntax Analyzer task
- Code Generator task
- Virtual Machine Interpreter task
- AST Interpreter task
Const MAX_INCLUDE_DEPTH = 5
Const MAX_MACROS = 100
Const MAX_CONSTS = 100
Const MAX_ARGS = 10
Type Macro
nombre As String
params As String
expr As String
End Type
Function BuscarEspacio(s As String) As Integer
For i As Integer = 1 To Len(s)
If Mid(s, i, 1) = " " Or Mid(s, i, 1) = Chr(9) Then Return i
Next
Return 0
End Function
Function TrimAmbos(s As String) As String
Dim As Integer i = 1, j = Len(s)
While i <= j Andalso (Mid(s, i, 1) = " " Or Mid(s, i, 1) = Chr(9))
i += 1
Wend
While j >= i Andalso (Mid(s, j, 1) = " " Or Mid(s, j, 1) = Chr(9))
j -= 1
Wend
If i > j Then Return ""
Return Mid(s, i, j - i + 1)
End Function
Sub ExtraerMacro(linea As String, Byref nombre As String, Byref params As String, Byref expr As String)
Dim As Integer p1 = Instr(linea, "(")
Dim As Integer p2 = Instr(linea, ")")
If p1 > 0 And p2 > p1 Then
nombre = TrimAmbos(Mid(linea, 1, p1 - 1))
params = TrimAmbos(Mid(linea, p1 + 1, p2 - p1 - 1))
expr = TrimAmbos(Mid(linea, p2 + 1))
Else
nombre = ""
params = ""
expr = ""
End If
End Sub
Sub ExtraerArgs(args As String, argList() As String, Byref nArgs As Integer)
nArgs = 0
Dim As Integer i = 1, j = 1, l = Len(args)
While i <= l
While i <= l Andalso (Mid(args, i, 1) = " " Or Mid(args, i, 1) = Chr(9))
i += 1
Wend
j = i
While j <= l Andalso Mid(args, j, 1) <> ","
j += 1
Wend
argList(nArgs) = TrimAmbos(Mid(args, i, j - i))
nArgs += 1
i = j + 1
Wend
End Sub
Function SustituirMacro(expr As String, params() As String, args() As String, nParams As Integer) As String
Dim As String res = ""
Dim As Integer i = 1
While i <= Len(expr)
Dim As Boolean encontrado = False
For j As Integer = 0 To nParams - 1
Dim As String pname = params(j)
Dim As Integer lpn = Len(pname)
If lpn > 0 Then
If Mid(expr, i, lpn) = pname Then
res &= args(j)
i += lpn
encontrado = True
Exit For
End If
End If
Next
If Not encontrado Then
res &= Mid(expr, i, 1)
i += 1
End If
Wend
Return res
End Function
Function SustituirConstantes(linea As String, consts() As String, vals() As String, nConst As Integer) As String
Dim As String res = ""
Dim As Integer i = 1
While i <= Len(linea)
Dim As Boolean hecho = False
For j As Integer = 0 To nConst - 1
Dim As String cname = consts(j)
Dim As Integer lcn = Len(cname)
If lcn > 0 Then
If Mid(linea, i, lcn) = cname Then
res &= vals(j)
i += lcn
hecho = True
Exit For
End If
End If
Next
If Not hecho Then
res &= Mid(linea, i, 1)
i += 1
End If
Wend
Return res
End Function
Function ExpandirMacros(linea As String, macros() As Macro, nMacros As Integer, _
consts() As String, vals() As String, nConst As Integer) As String
Dim As String res = ""
Dim As Integer i = 1
While i <= Len(linea)
If Mid(linea, i, 1) = "#" Then
Dim As Integer cierra = Instr(i + 1, linea, "#")
If cierra > 0 Then
Dim As String mcall = Mid(linea, i + 1, cierra - i - 1)
Dim As Integer p1 = Instr(mcall, "(")
Dim As Integer p2 = Instr(mcall, ")")
If p1 > 0 And p2 > p1 Then
Dim As String mname = TrimAmbos(Mid(mcall, 1, p1 - 1))
Dim As String argsStr = TrimAmbos(Mid(mcall, p1 + 1, p2 - p1 - 1))
Dim As Boolean encontrado = False
For j As Integer = 0 To nMacros - 1
If macros(j).nombre = mname Then
Dim As String paramList(0 To MAX_ARGS-1), argList(0 To MAX_ARGS-1)
Dim As Integer nParams = 0, nArgs = 0
ExtraerArgs(macros(j).params, paramList(), nParams)
ExtraerArgs(argsStr, argList(), nArgs)
If nArgs = nParams Then
Dim As String exprExpandida = SustituirMacro(macros(j).expr, paramList(), argList(), nParams)
exprExpandida = SustituirConstantes(exprExpandida, consts(), vals(), nConst)
res &= exprExpandida
encontrado = True
Exit For
End If
End If
Next
If Not encontrado Then res &= Mid(linea, i, cierra - i + 1)
i = cierra + 1
Else
res &= Mid(linea, i, cierra - i + 1)
i = cierra + 1
End If
Else
res &= Mid(linea, i)
Exit While
End If
Else
res &= Mid(linea, i, 1)
i += 1
End If
Wend
Return res
End Function
Sub PreprocesarArchivo(nombreArchivo As String, Byref salida As String, _
consts() As String, vals() As String, Byref nConst As Integer, _
macros() As Macro, Byref nMacros As Integer, _
depth As Integer, debug As Integer)
If depth > MAX_INCLUDE_DEPTH Then
Print "Error: Too much includes depth"
End 1
End If
Dim As Integer ff = Freefile()
If Open(nombreArchivo For Input As #ff) <> 0 Then
Print "It cannot be opened "; nombreArchivo
End 1
End If
Dim As Integer i, esp
Dim As String nombre, valor, def
Dim As Boolean yaExiste = False
While Not Eof(ff)
Dim As String linea
Line Input #ff, linea
Dim As String trimLinea = TrimAmbos(linea)
If Left(trimLinea, 8) = "#include" Then
Dim As Integer q1 = Instr(trimLinea, Chr(34))
Dim As Integer q2 = Instr(q1 + 1, trimLinea, Chr(34))
If q1 > 0 And q2 > q1 Then
Dim As String incfile = Mid(trimLinea, q1 + 1, q2 - q1 - 1)
If debug Then salida &= "/* Include " & incfile & " */" & Chr(10)
PreprocesarArchivo(incfile, salida, consts(), vals(), nConst, macros(), nMacros, depth + 1, debug)
If debug Then salida &= "/* End " & incfile & " */" & Chr(10)
End If
Elseif Left(trimLinea, 7) = "#define" Then
def = TrimAmbos(Mid(trimLinea, 8))
If Instr(def, "(") > 0 And Instr(def, ")") > Instr(def, "(") Then
Dim As String params, expr
ExtraerMacro(def, nombre, params, expr)
yaExiste = False
For i = 0 To nMacros - 1
If macros(i).nombre = nombre Then yaExiste = True
Next
If Not yaExiste Then
macros(nMacros).nombre = nombre
macros(nMacros).params = params
macros(nMacros).expr = expr
nMacros += 1
If debug Then salida &= "/* Define " & nombre & "(" & params & ") as " & expr & " */" & Chr(10)
End If
Else
esp = BuscarEspacio(def)
If esp > 0 Then
nombre = TrimAmbos(Left(def, esp - 1))
valor = TrimAmbos(Mid(def, esp + 1))
Else
nombre = TrimAmbos(def)
valor = ""
End If
yaExiste = False
For i = 0 To nConst - 1
If consts(i) = nombre Then yaExiste = True
Next
If Not yaExiste Then
consts(nConst) = nombre
vals(nConst) = valor
nConst += 1
If debug Then salida &= "/* Define " & nombre & " as " & valor & " */" & Chr(10)
End If
End If
Elseif Left(trimLinea, 6) = "#const" Then
def = TrimAmbos(Mid(trimLinea, 7))
esp = BuscarEspacio(def)
If esp > 0 Then
nombre = TrimAmbos(Left(def, esp - 1))
valor = TrimAmbos(Mid(def, esp + 1))
Else
nombre = TrimAmbos(def)
valor = ""
End If
yaExiste = False
For i = 0 To nConst - 1
If consts(i) = nombre Then yaExiste = True
Next
If Not yaExiste Then
consts(nConst) = nombre
vals(nConst) = valor
nConst += 1
If debug Then salida &= "/* Const " & nombre & " = " & valor & " */" & Chr(10)
End If
Else
Dim As String linea2 = ExpandirMacros(linea, macros(), nMacros, consts(), vals(), nConst)
linea2 = SustituirConstantes(linea2, consts(), vals(), nConst)
salida &= linea2 & Chr(10)
End If
Wend
Close #ff
End Sub
' --- Main program ---
Dim As String infile = "program.src"
Dim As String prefile = "program.pre"
Dim debug As Integer = 0
Dim As String salida = ""
Dim As String consts(MAX_CONSTS), vals(MAX_CONSTS)
Dim As Macro macros(MAX_MACROS)
Dim As Integer nConst = 0, nMacros = 0
If Command(1) = "-d" Then
debug = 1
infile = Command(2)
End If
PreprocesarArchivo(infile, salida, consts(), vals(), nConst, macros(), nMacros, 0, debug)
If prefile = "" Then
Print salida
Else
Dim ff As Integer = Freefile()
Open prefile For Output As #ff
Print #ff, salida;
Close #ff
Print "Saved output in "; prefile
End If
Sleep
""" Rosetta Code task Compiler/Preprocessor task """
""" If the line is a macro definition, add the macro to macros. """
function addmacro!(macros, line)
macroname, comment = "", ""
if (m = match(r"#define\s+(\w[\w\d]*)\(([^\)]+)\)\s+(.+)", line)) != nothing
macroname, argstring, definition = m.captures
comment = "/* Define $macroname($argstring) as $definition */\n"
@assert !haskey(macros, macroname) "Duplicate macro names are not allowed"
argv = strip.(split(argstring, r"\s*,\s*"))
@assert allunique(argv) "Parameter argument symbols must be different from each other"
def = " " * definition
defstrings, argnums = String[], Int[]
for m in reverse(collect(eachmatch(Regex(join(argv, "|")), def)))
cutposition = m.offset + length(m.match)
pushfirst!(defstrings, def[begin+cutposition-1:end])
pushfirst!(argnums, findfirst(==(m.match), argv))
def = def[begin:m.offset-1]
end
pushfirst!(defstrings, def)
macros[macroname] = (defstrings, argnums)
elseif (m = match(r"#define\s+(\w[\w\d]*)(?:\(\))?\s+(.+)", line)) != nothing
macroname, definition = m.captures
comment = "/* Define $macroname as $definition */\n"
macros[macroname] = ([string(definition)], Int[])
else
return false, ""
end
return true, comment
end
""" If the line contains macro or macros, substitute all and return results. """
function replaceifmacro(macros, line; withinhashtag = true)
replacedline, allmacronames, usedmacros = line, join(keys(macros), "|"), String[]
for m in reverse(
collect(
eachmatch(
Regex(
withinhashtag ? "#(" * allmacronames * raw")(?:(?:\(([^\)]+)\)#)|#)" :
"(" * allmacronames * raw")(?:(?:\(([^\)]+)\))?)",
),
replacedline,
),
),
)
push!(usedmacros, string(m.captures[1]))
if m.offsets[end] != 0 # has arguments
args = split(m.captures[end], r"\s*,\s*")
for (i, arg) in enumerate(args)
used, newtext = replaceifmacro(macros, arg; withinhashtag = false)
if !isempty(used)
submacro = first(used)
push!(usedmacros, submacro)
args[i] = macros[submacro][1][1]
end
end
strings, nums = macros[m.captures[1]]
s =
first(strings) *
prod([args[n] * strings[i+1] for (i, n) in enumerate(nums)])
replacedline =
replacedline[begin:m.offsets[1]-2] *
s *
replacedline[m.offset+length(m.match):end]
else
replacedline =
replacedline[begin:m.offsets[1]-2] *
macros[m.captures[1]][1][1] *
replacedline[m.offset+length(m.match):end]
end
end
return usedmacros, replacedline
end
""" If a line starts with #include, return the lines in the include file. """
function processinclude(line)
lines, fname = String[], ""
if (m = match(r"#include\s+\"([^\"]+)\"", line)) != nothing
fname = first(m.captures)
lines = readlines(fname, keep = true)
end
return fname, lines
end
""" Preprocess the file to prepare it for the Rosetta Code lexical analyzer task. """
function preprocess(instream, outstream, debug)
lines = readlines(instream, keep = true)
macros = Dict{String,Tuple{Vector{String},Vector{Int}}}()
linesread = 0
while !isempty(lines)
line = popfirst!(lines)
linesread += 1
if startswith(line, '#')
fname, includelines = processinclude(line)
if !isempty(fname)
if debug
pushfirst!(includelines, """/* Include $fname */\n""")
push!(includelines, """/* End $fname */\n""")
end
lines = append!(includelines, lines)
elseif startswith(line, r"#define\s")
gotmacro, comment = addmacro!(macros, line)
gotmacro && debug && print(outstream, comment)
else
error("Unknown preprocessor directive in line: $line")
end
else
usedmacros, replacedline = replaceifmacro(macros, line)
if !isempty(usedmacros)
debug && print(outstream, "/* Used " * join(usedmacros, ", ", " and ") * " */\n")
line = replacedline
end
print(outstream, line)
end
end
return linesread
end
""" Process command line, open files if needed, hand off to function `func`, close files """
function runwithopts(func, minargs = 0, maxargs = 3)
minargs <= length(ARGS) <= maxargs || error("Wrong number of arguments ($minargs:$maxargs)")
debug, infile, outfile = false, "", ""
for arg in ARGS
if arg == "-d" || arg == "-debug"
debug = true
elseif isempty(infile)
infile = arg
elseif isempty(outfile)
outfile = arg
end
end
ioin = isempty(infile) ? stdin : open(infile, "r")
ioout = isempty(outfile) ? stdout : open(outfile, "w")
func(ioin, ioout, debug)
!isempty(infile) && close(ioin)
!isempty(outfile) && close(ioout)
end
runwithopts(preprocess)
- Output:
Same output as Phix entry.
No attempt to implement command line arguments, obviously trivial on desktop/Phix but not possible under pwa/p2js, aka within a browser.
-- -- demo\rosetta\Compiler\preprocess.exw -- ==================================== -- -- Note this uses js_open() and js_gets() directly, to avoid distributing another two files. -- Also implemented as a standalone demonstration of the general approach, and as such -- might require a bit more work to integrate this properly into the likes of next_ch(), -- unless of course you write it out to disk and/or add some kind of js_write() function. -- Also as noted this won't cope particularly well with #macro("1st,first","2nd")#, etc. -- In other words splitting up the parameters may need to be made significantly smarter. -- with javascript_semantics include core.e -- (see Compiler/lexical_analyzer#Phix - specifcally js_io.e's Source.t) sequence stack, includes, defines, arglst, bodies integer stack_ptr procedure begin(string filename) -- (to allow with and without comments, sequentially, and -- specifically not moaning about things being redefined) stack = repeat(0,5) -- (limited as per task description) includes = repeat("?",5) -- "" defines = {} -- eg "area(h, w) h * w" -> "area" arglst = {} -- -1 if () absent, else eg {"h","w"} bodies = {} -- eg "area(h, w) h * w" -> {1," * ",2} stack_ptr = 1 stack[stack_ptr] = js_open(filename) end procedure function get_word(string line, integer k=1) string word = "" for ch in line[k..$] do if not find(charmap[ch],{LETTER,DIGIT}) then exit end if word &= ch end for return word end function function preprocess(string fragment, bool comments) string word = get_word(fragment) integer k = find(word,defines) assert(k!=0,"no such macro:%s",{word}) sequence used = {word}, body = deep_copy(bodies[k]) fragment = fragment[length(word)+1..$] object args = arglst[k] if sequence(args) then assert(fragment[1]='(' and fragment[$]=')') fragment = fragment[2..$-1] // NB: won't cope with eg #macro("1st,first","2nd")#, etc. sequence params = apply(split(fragment,','),trim) assert(length(params)==length(args)) for i=1 to length(body) do if integer(body[i]) then word = params[body[i]] k = find(word,defines) if k then // (this /might/ want to be recursive...) used = append(used,word) assert(atom(arglst[k])) // placeholder word = join(bodies[k],"") end if body[i] = word end if end for else assert(fragment="") end if if comments then printf(1,"/* Use %s */\n",{join(used,", ",", and ")}) end if string replacement = join(body,"") return replacement end function for comments in {false,true} do printf(1,"with%s comments:\n",{iff(comments?"":"out")}) begin("Source.t") while stack_ptr do object oneline = js_gets(stack[stack_ptr]) if oneline=EOF then if comments and stack_ptr>1 then printf(1,"/* End %s */\n",{includes[stack_ptr]}) end if stack_ptr -= 1 else integer k = find('#',oneline) if k then string word = get_word(oneline,k+1) if word="include" then stack_ptr += 1 assert(k=1) -- 10 is length("#include ")+1 oneline = trim(oneline[10..$],` "`) stack[stack_ptr] = js_open(oneline) if comments then printf(1,"/* Include %s */\n",{oneline}) includes[stack_ptr] = oneline end if elsif word="define" then assert(k=1) -- 9 is length("#define ")+1 word = get_word(oneline,9) assert(not find(word,defines)) defines = append(defines,word) oneline = trim(oneline[9+length(word)..$]) sequence body = {} if oneline[1]='(' then k = find(')',oneline,2) assert(k>0,"closing parenthesis missing") sequence args = apply(split(oneline[2..k-1],','),trim) oneline = trim(oneline[k+1..$]) string fixed = "" while length(oneline) do word = get_word(oneline) if length(word)=0 then fixed &= oneline[1] oneline = oneline[2..$] else k = find(word,args) if k then if length(fixed) then body = append(body,fixed) fixed = "" end if body = append(body,k) else fixed &= word end if oneline = oneline[length(word)+1..$] end if end while if length(fixed) then body = append(body,fixed) fixed = "" end if arglst = append(arglst,args) else body = {oneline} arglst = append(arglst,-1) end if bodies = append(bodies,body) if comments then object al = arglst[$] string n = defines[$], a = iff(atom(al)?"":sprintf("(%s)",{join(al,',')})) sequence b = deep_copy(bodies[$]) for i=1 to length(b) do if atom(b[i]) then b[i] = al[b[i]] end if end for b = join(b,"") printf(1,"/* Define %s%s as %s */\n",{n,a,b}) end if else while k do integer l = find('#',oneline,k+1) assert(l!=0,"missing closing #") string fragment = oneline[k+1..l-1], replacement = preprocess(fragment,comments) oneline[k..l] = replacement k = find('#',oneline,k+length(replacement)-1) end while printf(1,"%s\n",{oneline}) end if else printf(1,"%s\n",{oneline}) end if end if end while printf(1,"\n") end for --close_files()
- Output:
without comments: area = 6 * 5; with comments: /* Include Header.h */ /* Define area(h,w) as h * w */ /* End Header.h */ /* Define width as 5 */ /* Define height as 6 */ /* Use area, height, and width */ area = 6 * 5;
#!/usr/bin/env python
"""Rosetta Code compiler/preprocessor. Requires Python >= 3.7."""
import re
import sys
from typing import Dict
from typing import Iterator
from typing import List
from typing import NamedTuple
from typing import Optional
from typing import TextIO
from typing import Tuple
MAX_INCLUDE_DEPTH = 5
TOKEN_INCLUDE = "INCLUDE"
TOKEN_CONSTANT = "CONSTANT"
TOKEN_MACRO = "MACRO"
TOKEN_CALL = "CALL"
TOKEN_STRING = "STRING"
TOKEN_COMMENT = "COMMENT"
TOKEN_LITERAL = "LITERAL"
TOKEN_ILLEGAL = "ILLEGAL"
class Token(NamedTuple):
kind: str
name: str
params: str
expr: str
start: int
end: int
FILENAME_PATTERN = r"[_a-zA-Z][_a-zA-Z0-9\.]*"
IDENT_PATTERN = r"[_a-zA-Z][_a-zA-Z0-9]*"
PARAMS_PATTERN = r"[_a-zA-Z0-9\., \t]*?"
TOKEN_RULES = (
(
TOKEN_STRING,
r"\"[^\"\n]*?\"",
),
(
TOKEN_COMMENT,
r"/\*.*?\*/",
),
(
TOKEN_LITERAL,
r"[^#]+",
),
(
TOKEN_INCLUDE,
rf"^\#include[ \t]+\"(?P<filename>{FILENAME_PATTERN})\"\s*?$",
),
(
TOKEN_CONSTANT,
rf"^\#define[ \t]+(?P<constant>{IDENT_PATTERN}) +(?P<constant_expr>.*?)$",
),
(
TOKEN_MACRO,
rf"^\#define[ \t](?P<macro>{IDENT_PATTERN})"
rf"\((?P<macro_params>{PARAMS_PATTERN})\) +(?P<macro_expr>.*?)$",
),
(
TOKEN_CALL,
rf"\#(?P<call>{IDENT_PATTERN})\((?P<call_params>{PARAMS_PATTERN})\)\#",
),
(
TOKEN_ILLEGAL,
r".",
),
)
RE_TOKENS = re.compile(
"|".join(f"(?P<{name}>{pattern})" for name, pattern in TOKEN_RULES),
re.MULTILINE,
)
class PreprocessorError(Exception):
def __init__(
self,
*args: object,
source: str,
filename: str,
token: Token,
) -> None:
super().__init__(*args)
self.source = source
self.token = token
self.filename = filename
def __str__(self) -> str:
msg = super().__str__()
line_num = self.source[: self.token.start].count("\n") + 1
return f"{msg} ({self.filename}:{line_num})"
def tokenize(source: str, filename: str) -> Iterator[Token]:
for match in RE_TOKENS.finditer(source):
kind = match.lastgroup
if kind in (TOKEN_LITERAL, TOKEN_COMMENT, TOKEN_STRING):
yield Token(
TOKEN_LITERAL,
"",
"",
match.group(),
match.start(),
match.end(),
)
elif kind == TOKEN_INCLUDE:
yield Token(
TOKEN_INCLUDE,
"",
"",
match.group("filename"),
match.start(),
match.end(),
)
elif kind == TOKEN_CONSTANT:
yield Token(
kind,
match.group("constant"),
"",
match.group("constant_expr"),
match.start(),
match.end(),
)
elif kind == TOKEN_MACRO:
yield Token(
kind,
match.group("macro"),
match.group("macro_params"),
match.group("macro_expr"),
match.start(),
match.end(),
)
elif kind == TOKEN_CALL:
yield Token(
kind,
match.group("call"),
match.group("call_params"),
"",
match.start(),
match.end(),
)
elif kind == TOKEN_ILLEGAL:
# Probably part of an invalid macro call
yield Token(
TOKEN_LITERAL,
"",
"",
match.group(),
match.start(),
match.end(),
)
else:
raise PreprocessorError(
f"unexpected token kind {kind} ({match.group()!r})",
source=source,
filename=filename,
token=Token(
TOKEN_ILLEGAL,
"",
"",
match.group(),
match.start(),
match.end(),
),
)
def preprocess(
source: str,
filename: str,
stream: TextIO,
debug: bool = False,
constants: Optional[Dict[str, str]] = None,
include_depth: int = 0,
macros: Optional[Dict[str, Tuple[str, int]]] = None,
) -> None:
constants = constants if constants is not None else {}
include_depth = include_depth
macros = macros if macros is not None else {}
left_strip = False
for token in tokenize(source, filename):
if token.kind == TOKEN_LITERAL:
if left_strip:
stream.write(_lstrip_one(token.expr))
left_strip = False
else:
stream.write(token.expr)
elif token.kind == TOKEN_CONSTANT:
if debug:
stream.write(f"/* Define {token.name} as {token.expr} */\n")
if token.name in constants:
raise PreprocessorError(
f"illegal constant redefinition '{token.name}'",
source=source,
filename=filename,
token=token,
)
constants[token.name] = token.expr
left_strip = True
elif token.kind == TOKEN_INCLUDE:
if include_depth + 1 > MAX_INCLUDE_DEPTH:
raise PreprocessorError(
"maximum include depth reached",
source=source,
filename=filename,
token=token,
)
if debug:
stream.write(f"/* Include {token.expr} */\n")
with open(token.expr) as fd:
preprocess(
fd.read(),
filename,
stream,
debug,
constants,
include_depth + 1,
macros,
)
if debug:
stream.write(f"/* End {token.expr} */\n")
left_strip = True
elif token.kind == TOKEN_MACRO:
if debug:
stream.write(
f"/* Define {token.name}({token.params}) as {token.expr} */\n"
)
if token.name in macros:
raise PreprocessorError(
f"illegal macro redefinition '{token.name}'",
source=source,
filename=filename,
token=token,
)
params = parse_parameters(token.params)
expr = parse_expression(params, token.expr)
macros[token.name] = (expr, len(params))
left_strip = True
elif token.kind == TOKEN_CALL:
params = parse_parameters(token.params)
expr, n_args = macros.get(token.name, ("", 0))
if debug:
if params:
used = [token.name, *params]
stream.write(f"/* Use {', '.join(used[:-1])} and {used[-1]} */ ")
else:
stream.write(f"/* Use {token.name} */ ")
if len(params) != n_args:
print(token.name, len(params), n_args, macros)
stream.write(source[token.start : token.end])
else:
stream.write(
substitute_constants(
constants,
expr.format(*params),
)
)
left_strip = False
else:
raise PreprocessorError(
f"unknown token kind {token}",
source=source,
filename=filename,
token=token,
)
def parse_parameters(params: str) -> List[str]:
return [param.strip() for param in params.split(",")]
def parse_expression(params: List[str], expr: str) -> str:
_params = {p: str(i) for i, p in enumerate(params)}
pattern = "|".join(rf"\b{param}\b" for param in params)
return re.sub(
f"({pattern})",
lambda m: f"{{{_params[m.group(0)]}}}",
expr,
)
def substitute_constants(constants: Dict[str, str], expr: str) -> str:
pattern = "|".join(rf"\b{const}\b" for const in constants)
return re.sub(
f"({pattern})",
lambda m: constants[m.group(0)],
expr,
)
def _lstrip_one(s: str) -> str:
"""Strip at most one newline from the left of `s`."""
if s and s[0] == "\n":
return s[1:]
return s
if __name__ == "__main__":
import argparse
parser = argparse.ArgumentParser(description="Rosetta Code compiler preprocessor.")
parser.add_argument(
"infile",
nargs="?",
type=argparse.FileType("r"),
default=sys.stdin,
help="source file to preprocess, '-' means stdin (default: stdin)",
)
parser.add_argument(
"outfile",
nargs="?",
type=argparse.FileType("w"),
default=sys.stdout,
help="destination file (default: stdout)",
)
parser.add_argument(
"--debug",
"-d",
action="store_true",
help="enable debugging output (default: false)",
)
args = parser.parse_args()
preprocess(args.infile.read(), args.infile.name, args.outfile, debug=args.debug)
- Output:
Command line options. Show the help message and exit.
$ ./preproc.py --help usage: preproc.py [-h] [--debug] [infile] [outfile] Rosetta Code compiler preprocessor. positional arguments: infile source file to preprocess, '-' means stdin (default: stdin) outfile destination file (default: stdout) options: -h, --help show this help message and exit --debug, -d enable debugging output (default: false)
Where Source.t and Header.h contain the source code shown in the task description.
$ ./preproc.py Source.t area = 6 * 5;
And with debugging enabled. Notice debug output appears immediately before a macro call rather than on the line above.
$ ./preproc.py source.t --debug /* Include Header.h */ /* Define area(h, w) as h * w */ /* End Header.h */ /* Define width as 5 */ /* Define height as 6 */ area = /* Use area, height and width */ 6 * 5;
And piped to the lexer defined in the Lexical Analysis task.
$ ./preproc.py source.t | ./compiler_lex.py
1 1 Identifier area
1 6 Op_assign
1 8 Integer 6
1 10 Op_multiply
1 12 Integer 5
1 13 Semicolon
2 1 End_of_input
A fairly naive solution compared to the complexities of a modern C pre-processor.
I've made the simplifying assumption that macro parameters in a macro definition will always be separated from other tokens by at least one space.
I've also assumed that the header files will always be actual files, and never entered from the console.
Note that the program errors out if there are any syntax or other errors when defining the macros.
import "os" for Process
import "./ioutil" for FileUtil, File, Input
import "./str" for Char
import "./pattern" for Pattern
import "./seq" for Lst, Stack
var isIdentChar = Fn.new { |c| Char.isAsciiAlphaNum(c) || c == "_" }
var isIdent = Fn.new { |s|
if (s == "") return false
if (Char.isDigit(s[0])) return false
return s.all { |c| isIdentChar.call(c) }
}
var clargs = Process.arguments
if (clargs.count > 3) {
System.print("There can't be more than 3 command line arguments:
-d // debug mode, comments will be included in output
input // filename: if absent or == console, gets input from console
output // filename: if absent or == console, sends output to console")
return
}
var debug = clargs.contains("-d") || clargs.contains("--debug")
if (debug) {
clargs.remove("-d")
clargs.remove("--debug")
}
var inputFileName = "console"
if (clargs.count > 0) inputFileName = clargs[0]
var lines
if (inputFileName != "console") {
lines = FileUtil.readLines(inputFileName)
} else {
var n = Input.integer("How many lines are to be entered? : ", 1)
System.print("\nOK, enter the lines and press enter after each one.\n")
lines = List.filled(n, null)
for (i in 0...n) lines[i] = Input.text("")
System.print()
}
var macros = []
var comments = []
var used = []
var includes = Stack.new()
var i = 0
while (i < lines.count) {
var line = lines[i].trim()
if (line == "" || !line.startsWith("#")) {
i = i + 1
} else if (line.startsWith("#include")) {
var fname = line[8..-1].trimStart()
if (fname.count < 3 || fname[0] != "\"" || fname[-1] != "\"") {
Fiber.abort("'#include' directive must be followed by a non-empty string.")
}
var lines2 = FileUtil.readLines(fname[1..-2])
if (includes.count == 5) {
Fiber.abort("Can't have more than 5 active 'include' files.")
} else {
includes.push([fname, i + lines2.count - 1])
if (debug) comments.add("/* Include Header %(fname) */")
}
lines = lines[0...i] + lines2 + lines[i+1..-1]
} else if (line.startsWith("#define")) {
line = line[7..-1].trimStart()
if (line == "") Fiber.abort("Missing macro name.")
var name = ""
var j = 0
while (j < line.count) {
var c = line[j]
if (isIdentChar.call(c)) name = name + c else break
j = j + 1
}
if (name == "") Fiber.abort("Missing macro name.")
if (!isIdent.call(name)) Fiber.abort("Macro name is not a valid identifier.")
if (macros.any { |macro| macro[0] == name }) Fiber.abort("Macro '%(name)' cannot be redefined.")
if (j == line.count) Fiber.abort("Missing macro definition.")
var paramStr = ""
var params = null
if (line[j] == "(") {
j = j + 1
var k = line.indexOf(")", j)
if (k == -1) Fiber.abort("Missing ')' in macro parameter list.")
if (k == j) {
params = []
} else {
paramStr = line[j...k]
params = paramStr.split(",")
params = params.map { |param| param.trim() }.toList
if (!params.all { |param| isIdent.call(param) }) {
Fiber.abort("Macro parameter is not a valid identifier.")
}
}
j = k + 1
}
if (j == line.count) Fiber.abort("Missing macro definition.")
var defn = line[j..-1].trimStart()
macros.add([name, params, defn])
if (debug) {
if (params == null) {
comments.add("/* Define %(name) as %(defn) */")
} else {
comments.add("/* Define %(name)(%(params.toString[1...-1])) as %(defn) */")
}
}
lines.removeAt(i)
} else {
Fiber.abort("Unknown directive.")
}
if (debug) {
while (includes.count > 0 && i >= includes.peek()[1]) {
comments.add("/* End %(includes.pop()[0]) */")
}
}
}
var src = lines.where { |line| line != "" }.join("\n")
for (macro in macros) {
var name = macro[0]
var params = macro[1]
var defn = macro[2]
var p
if (params == null) {
p = Pattern.new("/X[%(name)]~/X")
} else if (params.count == 0) {
p = Pattern.new("[/#%(name)()/#]")
} else if (params.count > 0) {
p = Pattern.new("[/#%(name)(+1^))/#]")
}
var m = null
while (m = p.find(src)) {
var span = m.captures[0].span
if (params == null || params.count == 0) {
src = src[0...span[0]] + defn + src[span[1]+1..-1]
used.add(name)
} else {
var argStr = m.captures[0].text
var ix1 = argStr.indexOf("(") + 1
var ix2 = argStr.indexOf(")") - 1
argStr = argStr[ix1..ix2]
var args = argStr.split(",")
if (args.count == params.count) {
var temp = " " + defn + " "
for (i in 0...args.count) {
temp = temp.replace(" " + params[i] + " ", " " + args[i].trim() + " ")
}
src = src[0...span[0]] + temp.trim() + src[span[1]+1..-1]
used.add(name)
}
}
}
}
if (debug) {
while (includes.count > 0) {
comments.add("/* End %(includes.pop()[0]) */")
}
}
used = Lst.distinct(used)
if (used.count > 0) {
var temp = (used.count == 1) ? used[0] : used[0..-2].join(", ") + " and " + used[-1]
if (debug) comments.add("/* Used %(temp) */")
}
if (debug) comments = comments.join("\n")
var outputFileName = "console"
if (clargs.count > 1) outputFileName = clargs[1]
if (outputFileName == "console") {
System.print("Output:\n")
if (debug) System.print(comments)
System.print(src)
} else {
File.create(outputFileName) { |file|
if (debug) {
file.writeBytes(comments)
file.writeBytes("\n")
}
file.writeBytes(src)
file.writeBytes("\n")
}
}
- Output:
Using the example files;
$ wren-cli Compiler_Preprocessor.wren -d How many lines are to be entered? : 4 OK, enter the lines and press enter after each one. #include "Header.h" #define width 5 #define height 6 area = #area(height, width)#; Output: /* Include Header "Header.h" */ /* Define area(h, w]) as h * w */ /* End "Header.h" */ /* Define width as 5 */ /* Define height as 6 */ /* Used area, width and height */ area = 6 * 5;
Or adding another header file to make the example slightly more interesting:
~~ Header.h ~~ #define area(h, w) h * w #include "Header2.h" ~~ Header2.h ~~ #define depth 7 #define volume(h, w, d) h * w * d ~~ Source.t ~~ #include "Header.h" #define width 5 #define height 6 area = #area(height, width)#; volume = #volume(height, width, depth)#;
- Output:
$ wren-cli Compiler_Preprocessor.wren -d Source.t Output: /* Include Header "Header.h" */ /* Define area(h, w) as h * w */ /* Include Header "Header2.h" */ /* Define depth as 7 */ /* Define volume(h, w, d) as h * w * d */ /* End "Header2.h" */ /* End "Header.h" */ /* Define width as 5 */ /* Define height as 6 */ /* Used area, depth, volume, width and height */ area = 6 * 5; volume = 6 * 5 * 7;