ref: d916a4c3823f55227ffae35738c2497256e307b5
dir: /appl/cmd/mash/lex.b/
#
# Lexical analyzer.
#
lexdebug : con 0;
#
# Import tokens from parser.
#
Land,
Lat,
Lbackq,
Lcaret,
Lcase,
Lcolon,
Lcolonmatch,
Lcons,
Ldefeq,
Lelse,
Leof,
Leq,
Leqeq,
Lerror,
Lfn,
Lfor,
Lgreat,
Lgreatgreat,
Lhd,
Lif,
Lin,
Llen,
Lless,
Llessgreat,
Lmatch,
Lmatched,
Lnot,
Lnoteq,
Loffcurly,
Loffparen,
Loncurly,
Lonparen,
Lpipe,
Lquote,
Lrescue,
Lsemi,
Ltl,
Lwhile,
Lword
: import Mashparse;
KWSIZE: con 31; # keyword hashtable size
NCTYPE: con 128; # character class array size
ALPHA,
NUMERIC,
ONE,
WS,
META
: con 1 << iota;
keywords := array[] of
{
("case", Lcase),
("else", Lelse),
("fn", Lfn),
("for", Lfor),
("hd", Lhd),
("if", Lif),
("in", Lin),
("len", Llen),
("rescue", Lrescue),
("tl", Ltl),
("while", Lwhile)
};
ctype := array[NCTYPE] of
{
0 or ' ' or '\t' or '\n' or '\r' or '\v' => WS,
':' or '#' or ';' or '&' or '|' or '^' or '$' or '=' or '@'
or '~' or '`'or '{' or '}' or '(' or ')' or '<' or '>' => ONE,
'a' to 'z' or 'A' to 'Z' or '_' => ALPHA,
'0' to '9' => NUMERIC,
'*' or '[' or ']' or '?' => META,
* => 0
};
keytab: ref HashTable;
#
# Initialize hashtable.
#
initlex()
{
keytab = hash->new(KWSIZE);
for (i := 0; i < len keywords; i++) {
(s, v) := keywords[i];
keytab.insert(s, HashVal(v, 0.0, nil));
}
}
#
# Keyword value, or -1.
#
keyval(i: ref Item): int
{
if (i.op != Iword)
return -1;
w := i.word;
if (w.flags & Wquoted)
return -1;
v := keytab.find(w.text);
if (v == nil)
return -1;
return v.i;
}
#
# Attach a source file to an environment.
#
Env.fopen(e: self ref Env, fd: ref Sys->FD, s: string)
{
in := bufio->fopen(fd, Bufio->OREAD);
if (in == nil)
e.error(sys->sprint("could not fopen %s: %r\n", s));
e.file = ref File(in, s, 1, 0);
}
#
# Attach a source string to an environment.
#
Env.sopen(e: self ref Env, s: string)
{
in := bufio->sopen(s);
if (in == nil)
e.error(sys->sprint("Bufio->sopen failed: %r\n"));
e.file = ref File(in, "<string>", 1, 0);
}
#
# Close source file.
#
fclose(e: ref Env, c: int)
{
if (c == Bufio->ERROR)
readerror(e, e.file);
e.file.in.close();
e.file = nil;
}
#
# Character class routines.
#
isalpha(c: int): int
{
return c >= NCTYPE || (c >= 0 && (ctype[c] & ALPHA) != 0);
}
isalnum(c: int): int
{
return c >= NCTYPE || (c >= 0 && (ctype[c] & (ALPHA | NUMERIC)) != 0);
}
isdigit(c: int): int
{
return c >= 0 && c < NCTYPE && (ctype[c] & NUMERIC) != 0;
}
isquote(c: int): int
{
return c < NCTYPE && (c < 0 || (ctype[c] & (ONE | WS | META)) != 0);
}
isspace(c: int): int
{
return c >= 0 && c < NCTYPE && (ctype[c] & WS) != 0;
}
isterm(c: int): int
{
return c < NCTYPE && (c < 0 || (ctype[c] & (ONE | WS)) != 0);
}
#
# Test for an identifier.
#
ident(s: string): int
{
if (s == nil || !isalpha(s[0]))
return 0;
n := len s;
for (x := 1; x < n; x++) {
if (!isalnum(s[x]))
return 0;
}
return 1;
}
#
# Quote text.
#
enquote(s: string): string
{
r := "'";
j := 1;
n := len s;
for (i := 0; i < n; i++) {
c := s[i];
if (c == '\'' || c == '\\')
r[j++] = '\\';
r[j++] = c;
}
r[j] = '\'';
return r;
}
#
# Quote text if needed.
#
quote(s: string): string
{
n := len s;
for (i := 0; i < n; i++) {
if (isquote(s[i]))
return enquote(s);
}
return s;
}
#
# Test for single word and identifier.
#
Item.sword(i: self ref Item, e: ref Env): ref Item
{
if (i.op == Iword && ident(i.word.text))
return i;
e.report("malformed identifier: " + i.text());
return nil;
}
readerror(e: ref Env, f: ref File)
{
sys->fprint(e.stderr, "error reading %s: %r\n", f.name);
}
where(e: ref Env): string
{
if ((e.flags & EInter) || e.file == nil)
return nil;
return e.file.name + ":" + string e.file.line + ": ";
}
#
# Suck input (on error).
#
Env.suck(e: self ref Env)
{
if (e.file == nil)
return;
in := e.file.in;
while ((c := in.getc()) >= 0 && c != '\n')
;
}
#
# Lexical analyzer.
#
Env.lex(e: self ref Env, yylval: ref Mashparse->YYSTYPE): int
{
i, r: ref Item;
reader:
for (;;) {
if (e.file == nil)
return -1;
f := e.file;
in := f.in;
while (isspace(c := in.getc())) {
if (c == '\n')
f.line++;
}
if (c < 0) {
fclose(e, c);
return Leof;
}
case c {
':' =>
if ((d := in.getc()) == ':')
return Lcons;
if (d == '=')
return Ldefeq;
if (d == '~')
return Lcolonmatch;
if (d >= 0)
in.ungetc();
return Lcolon;
'#' =>
for (;;) {
if ((c = in.getc()) < 0) {
fclose(e, c);
return Leof;
}
if (c == '\n') {
f.line++;
continue reader;
}
}
';' =>
return Lsemi;
'&' =>
return Land;
'|' =>
return Lpipe;
'^' =>
return Lcaret;
'@' =>
return Lat;
'!' =>
if ((d := in.getc()) == '=')
return Lnoteq;
if (d >= 0)
in.ungetc();
return Lnot;
'~' =>
return Lmatch;
'=' =>
if ((d := in.getc()) == '>')
return Lmatched;
if (d == '=')
return Leqeq;
if (d >= 0)
in.ungetc();
return Leq;
'`' =>
return Lbackq;
'"' =>
return Lquote;
'{' =>
return Loncurly;
'}' =>
return Loffcurly;
'(' =>
return Lonparen;
')' =>
return Loffparen;
'<' =>
if ((d := in.getc()) == '>')
return Llessgreat;
if (d >= 0)
in.ungetc();
return Lless;
'>' =>
if ((d := in.getc()) == '>')
return Lgreatgreat;
if (d >= 0)
in.ungetc();
return Lgreat;
'\\' =>
if ((d := in.getc()) == '\n') {
f.line++;
continue reader;
}
if (d >= 0)
in.ungetc();
}
# Loop over "carets for free".
for (;;) {
if (c == '$')
(i, c) = getdollar(f);
else
(i, c) = getword(e, f, c);
if (i == nil)
return Lerror;
if (isterm(c) && c != '$')
break;
if (r != nil)
r = ref Item(Iicaret, nil, r, i, nil, nil);
else
r = i;
}
if (c >= 0)
in.ungetc();
if (r != nil)
yylval.item = ref Item(Iicaret, nil, r, i, nil, nil);
else if ((c = keyval(i)) >= 0)
return c;
else
yylval.item = i;
return Lword;
}
}
#
# Get $n or $word.
#
getdollar(f: ref File): (ref Item, int)
{
s: string;
in := f.in;
l := f.line;
o := Idollar;
if (isdigit(c := in.getc())) {
s[0] = c;
n := 1;
while (isdigit(c = in.getc()))
s[n++] = c;
o = Imatch;
} else {
if (c == '"') {
o = Idollarq;
c = in.getc();
}
if (isalpha(c)) {
s[0] = c;
n := 1;
while (isalnum(c = in.getc()))
s[n++] = c;
} else {
if (o == Idollar)
s = "$";
else
s = "$\"";
o = Iword;
}
}
return (ref Item(o, ref Word(s, 0, Src(l, f.name)), nil, nil, nil, nil), c);
}
#
# Get word with quoting.
#
getword(e: ref Env, f: ref File, c: int): (ref Item, int)
{
s: string;
in := f.in;
l := f.line;
wf := 0;
n := 0;
if (c == '\'') {
wf = Wquoted;
collect:
while ((c = in.getc()) >= 0) {
case c {
'\'' =>
c = in.getc();
break collect;
'\\' =>
c = in.getc();
if (c != '\'' && c != '\\') {
if (c == '\n')
continue collect;
if (c >= 0)
in.ungetc();
c = '\\';
}
'\n' =>
f.line++;
e.report("newline in quoted word");
return (nil, 0);
}
s[n++] = c;
}
} else {
do {
case c {
'*' or '[' or '?' =>
wf |= Wexpand;
}
s[n++] = c;
} while (!isterm(c = in.getc()) && c != '\'');
}
if (lexdebug && s == "exit")
exit;
return (ref Item(Iword, ref Word(s, wf, Src(l, f.name)), nil, nil, nil, nil), c);
}
#
# Get a line, mapping escape newline to space newline.
#
getline(in: ref Bufio->Iobuf): string
{
if (inchan != nil) {
alt {
b := <-inchan =>
if (inchan == nil)
return nil;
s := string b;
n := len s;
if (n > 1) {
while (s[n - 2] == '\\' && s[n - 1] == '\n') {
s[n - 2] = ' ';
s[n - 1] = ' ';
prprompt(1);
b = <-inchan;
if (b == nil)
break;
s += string b;
n = len s;
}
}
return s;
b := <-servechan =>
s := string b;
sys->print("%s", s);
return s;
}
} else {
s := in.gets('\n');
if (s == nil)
return nil;
n := len s;
if (n > 1) {
while (s[n - 2] == '\\' && s[n - 1] == '\n') {
s[n - 2] = ' ';
s[n - 1] = ' ';
prprompt(1);
t := in.gets('\n');
if (t == nil)
break;
s += t;
n = len s;
}
}
return s;
}
}
#
# Interactive shell loop.
#
Env.interactive(e: self ref Env, fd: ref Sys->FD)
{
in := bufio->fopen(fd, Sys->OREAD);
if (in == nil)
e.error(sys->sprint("could not fopen stdin: %r\n"));
e.flags |= EInter;
for (;;) {
prprompt(0);
if (startserve)
e.serve();
if ((s := getline(in)) == nil)
exitmash();
e.sopen(s);
parse->parse(e);
if (histchan != nil)
histchan <-= array of byte s;
}
}