67 lines
2.0 KiB
Plaintext
67 lines
2.0 KiB
Plaintext
// selfhost/cmd/w6a/lex.ww — port of cmd/w6a/lex.c.
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//
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// Character-level helpers for w6a's line-oriented parser. The parser
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// itself is in parse.ww; here we keep tokenisers for identifiers and
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// numbers so parse.ww stays focused on syntax.
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export fn isidstart(c: i32) bool = {
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if (c == 95) { return true; };
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if (c >= 65) { if (c <= 90) { return true; }; }; // A-Z
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if (c >= 97) { if (c <= 122) { return true; }; }; // a-z
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return false;
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};
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export fn isidcont(c: i32) bool = {
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if (isidstart(c)) { return true; };
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if (c >= 48) { if (c <= 57) { return true; }; }; // 0-9
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if (c == 46) { return true; }; // .
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return false;
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};
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// parsenum — read a leading [+-]?[0x|0X|0]?digits from p[0..n-1].
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// Returns (value, consumed). Stops at first non-digit.
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// Plain Plan 9-style: $123 / $0x1f / $-7. Decimal default; 0x prefix
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// for hex; 0 prefix for octal when followed by a digit (else just 0).
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export fn parsenum(p: *u8, n: u64) (i64, u64) = {
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let i: u64 = 0u64;
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let neg: bool = false;
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if (i < n) {
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if (p[i] == 45u8) { neg = true; i += 1u64; }
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else { if (p[i] == 43u8) { i += 1u64; }; };
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};
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let base: i64 = 10i64;
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if (i + 1u64 < n) {
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if (p[i] == 48u8) {
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if (p[i + 1u64] == 120u8) { base = 16i64; i += 2u64; }
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else { if (p[i + 1u64] == 88u8) { base = 16i64; i += 2u64; }
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else { if (p[i + 1u64] >= 48u8) { if (p[i + 1u64] <= 55u8) {
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base = 8i64; i += 1u64;
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};};};};
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};
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};
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let v: i64 = 0i64;
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let scan: bool = true;
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for (scan) {
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if (i >= n) { scan = false; }
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else {
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let c: u8 = p[i];
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let d: i64 = -1i64;
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if (c >= 48u8) { if (c <= 57u8) { d = (c - 48u8): i64; }; };
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if (d < 0i64) {
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if (base == 16i64) {
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if (c >= 97u8) { if (c <= 102u8) { d = (c - 97u8): i64 + 10i64; }; };
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if (c >= 65u8) { if (c <= 70u8) { d = (c - 65u8): i64 + 10i64; }; };
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};
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};
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if (d < 0i64) { scan = false; }
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else { if (d >= base) { scan = false; }
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else {
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v = v * base + d;
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i += 1u64;
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}; };
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};
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};
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if (neg) { v = -v; };
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return v, i;
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};
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