diff options
Diffstat (limited to 'ev')
| -rwxr-xr-x | ev | 73 |
1 files changed, 54 insertions, 19 deletions
@@ -12,7 +12,12 @@ BEGIN { # The rigth array contains binary operators which are right associative. right["="] = right["+="] = right["-="] = right["*="] = right["/="] = right["%="] = right["^="] = 1 right["^"] = 1 + start[")"] = "("; end["("] = ")" + start["}"] = "{"; end["{"] = "}" + start["]"] = "["; end["["] = "]" + + cl = 0 sp = pc = 0 # sp: stack pointer, pc: program counter. split("", code) split("", stack) @@ -21,19 +26,18 @@ BEGIN { } { line = $0 - parse() - run() + while (parse()) run() printf "> " } -function scan() { +function scan(peek) { ptok = tok sub(/^[ \t]+/, "", line) if (match(line, /^[0-9]([.0-9]*(e[+-]*)*[0-9])*/)) { # Literal number tok = "d" substr(line, 1, RLENGTH) } else if (match(line, /^([-=+|&]{2}|![=~]|[<>+-*\/^%]=)/)) { # Operator (2 chars) tok = substr(line, 1, RLENGTH) - } else if (match(line, /^([][}{)(,+-=?:]|[*\/÷\^])/)) { # Operator (1 char) + } else if (match(line, /^([][}{)(,+-=?:;]|[*\/÷\^])/)) { # Operator (1 char) tok = substr(line, 1, RLENGTH) } else if (match(line, /^[A-Za-z_][A-Za-z_0-9]*/)) { # Identifier tok = "v" substr(line, 1, RLENGTH) @@ -42,39 +46,66 @@ function scan() { } else { # Bad token tok = "b" substr(line, 1, 1) } - line = substr(line, RLENGTH+1) + if (!peek) line = substr(line, RLENGTH+1) return RLENGTH } -# TODO: unary operators, flow contror -function parse( ops, sl, i, b) { - b = i = length(code) +# TODO: unary operators, flow control, functions +# Recursive descent parser +function parse(want, got, ops, sl, i, b) { + b = cl while (scan() > 0) { - if (tok == "(") { + if (want && ! got) { + if ((got = tok) != want && want == "(") { print "missing " want; return 0 } + ops[++sl] = "done" + } + if (tok == ";") { + break + } else if (tok == "vif") { + if (! parse("(")) break + code[cl++] = "jzLif" ++lif + if (! parse("{")) break + if (scan(1) && tok == "velse") { + code[cl++] = "jLif" lif+1 + code[cl++] = "Lif" lif + sym["Lif" lif] = cl + if (! parse("{")) break + sym["Lif" ++lif] = cl + } else { + code[cl++] = "Lif" lif + sym["Lif" lif] = cl + } + } else if (tok in end) { ops[++sl] = tok - } else if (tok == ")") { - while (sl && ops[sl] != "(") code[i++] = ops[sl--] - sl-- + } else if (tok in start) { + while (sl && ops[sl] != start[tok]) code[cl++] = ops[sl--] + if (ops[--sl] == "done") { sl--; break } } else if (tok in prec) { # print "tok:" tok " ptok:" ptok - if (tok ~ /[+-*\/%^]?=/ && ptok ~ /^v/) sub(/^v/, "p", code[i-1]) # mutate var to pointer for assign + if (tok ~ /[+-*\/%^]?=/ && ptok ~ /^v/) sub(/^v/, "p", code[cl-1]) # Test precedence against ops, or associativity if same precedence. - while (sl && (prec[tok] < prec[ops[sl]] || prec[tok] == prec[ops[sl]] && !(ops[sl] in right))) { - code[i++] = ops[sl--] + while (sl && (prec[tok] < prec[ops[sl]] || + prec[tok] == prec[ops[sl]] && !(ops[sl] in right))) { + code[cl++] = ops[sl--] } ops[++sl] = tok } else { - code[i++] = tok + code[cl++] = tok } } - while (sl) code[i++] = ops[sl--] - for (j = b; j < i; j++) printf("%s ", code[j]); print "" + while (sl) { + # if (ops[sl] in end) { print "missing " end[ops[sl]]; return 0 } + if (want && ops[sl--] == "done") continue + code[cl++] = ops[sl--] + } + return cl-b } # TODO: if, while, function # Feel like being a stack machine. function run( c, i, l, t) { cl = length(code) + for (i = pc; i < cl; i++) printf("%s ", code[i]); print "" while (pc < cl) { c = code[pc] if (c == "+") { @@ -97,11 +128,15 @@ function run( c, i, l, t) { stack[++sp] = sym[substr(c, 2)] } else if (c ~ /^[d]/) { stack[++sp] = 0 + substr(c, 2) + } else if (c ~ /^jz/) { + if (!stack[sp--]) { pc = sym[substr(c, 3)]; continue } + } else if (c ~ /^L/) { + # nop on label } else { print "run: invalid instruction " c return } - # printf "c" pc ":%s", c; for (i = 1; i <= sp; i++) printf " " i ":" stack[i]; print "" + printf "c" pc ":%s", c; for (i = 1; i <= sp; i++) printf " " i ":" stack[i]; print "" # for (i in sym) print "sym[" i "]=" sym[i] pc++ } |