commit aa4564fc55ce2ed1c92d265cbc6c410e72d93473 Author: Alexander Rosenberg Date: Thu Apr 2 17:42:04 2026 -0700 Initial commit diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..631b937 --- /dev/null +++ b/.gitignore @@ -0,0 +1,3 @@ +lambda +*.o +compile_commands.json diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..f288702 --- /dev/null +++ b/LICENSE @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..44e4215 --- /dev/null +++ b/Makefile @@ -0,0 +1,22 @@ +DEBUG_FLAGS=-Og -g -fsanitize=address,undefined + +CC=gcc +CFLAGS=-std=c11 -D_FILE_OFFSET_BITS=64 -D_POSIX_C_SOURCE=200112L -Wall -Wextra $(DEBUG_FLAGS) +LD=gcc +LDFLAGS=$(DEBUG_FLAGS) + +lambda: main.o parse.o term.o + $(LD) $(LDFLAGS) -o $@ $^ + +%.o: %.c + $(CC) -c $(CFLAGS) -o $@ $< + +clean: + rm -f lambda *.o + +.PHONY: clean + +# Dependencies +main.o: parse.h term.h +parse.o: parse.h util.h +term.o: term.h diff --git a/README.md b/README.md new file mode 100644 index 0000000..41a06d4 --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +# lambda + +Simple clone of [Elsa](https://github.com/ucsd-progsys/elsa). diff --git a/main.c b/main.c new file mode 100644 index 0000000..a9439ee --- /dev/null +++ b/main.c @@ -0,0 +1,40 @@ +#include "parse.h" + +#include +#include +#include + +int main(int argc, const char **argv) { + if (argc < 2) { + printf("Not enough args!\n"); + return 1; + } + FILE *in = fopen(argv[1], "r"); + fseek(in, 0, SEEK_END); + off_t length = ftello(in); + rewind(in); + char *text = malloc(length); + fread(text, 1, length, in); + fclose(in); + TokenStream stream; + TokenStreamError err; + Token token; + token_stream_init(&stream, text, length); + while (!token_stream_is_eof(&stream)) { + token_stream_next(&stream, &token, &err); + if (token_stream_error_set(&err)) { + printf("Error at %zu:%zu: %s\n", err.pos.line, err.pos.column, + err.message); + free(text); + return 1; + } else { + char *ts = malloc(token.length + 1); + memcpy(ts, &text[token.pos.offset], token.length); + ts[token.length] = '\0'; + printf("%s: %s\n", token_type_to_string(token.type), ts); + free(ts); + } + } + free(text); + return 0; +} diff --git a/parse.c b/parse.c new file mode 100644 index 0000000..0ea9d1c --- /dev/null +++ b/parse.c @@ -0,0 +1,234 @@ +#include "parse.h" + +#include "util.h" + +#include +#include +#include +#include + +const char *token_type_to_string(TokenType type) { + static const char *const TYPES[] = { + [TOKEN_LET] = "LET", + [TOKEN_EVAL] = "EVAL", + [TOKEN_CONF] = "CONF", + [TOKEN_EQUALS] = "EQUALS", + [TOKEN_BACKSLASH] = "BACKSLASH", + [TOKEN_COLON] = "COLON", + [TOKEN_OPEN_PAREN] = "OPEN_PAREN", + [TOKEN_CLOSE_PAREN] = "CLOSE_PAREN", + [TOKEN_DEFINE] = "DEFINE", + [TOKEN_IDENT] = "IDENT", + [TOKEN_REDUCE] = "REDUCE", + [TOKEN_EOF] = "EOF", + }; + assert(type >= 0 && type < (sizeof(TYPES) / sizeof(TYPES[0]))); + return TYPES[type]; +} + +#define EOS -1 + +static bool is_whitespace(char c) { + return c == ' ' || c == '\t' || c == '\n'; +} + +static bool is_identifier(char c) { + return (c >= 'a' && c <= 'z') || c == '_'; +} + +static bool is_reduce(char c) { + return (c >= 'a' && c <= 'z') || c == '*' || c == '~' || c == ':'; +} + +static int peekc(TokenStream *stream) { + if (stream->pos.offset >= stream->src_len) { + return EOS; + } + return stream->src[stream->pos.offset]; +} + +static int popc(TokenStream *stream) { + if (stream->pos.offset >= stream->src_len) { + return EOS; + } + int c = stream->src[stream->pos.offset++]; + if (c == '\n') { + stream->pos.line_offset = stream->pos.offset; + ++stream->pos.line; + stream->pos.column = 0; + } else { + ++stream->pos.column; + } + return c; +} + +static void skip_whitespace(TokenStream *stream) { + while (is_whitespace(peekc(stream))) { + popc(stream); + } +} + +static void discard_until_newline(TokenStream *stream) { + int c; + while ((c = popc(stream)) != '\n' && c != EOS) { + } +} + +static TokenType typeof_single_char_token(char c) { + switch (c) { + case '=': + return TOKEN_EQUALS; + case '\\': + return TOKEN_BACKSLASH; + case ':': + return TOKEN_COLON; + case '(': + return TOKEN_OPEN_PAREN; + case ')': + return TOKEN_CLOSE_PAREN; + default: + abort(); + } +} + +static inline void set_token(Token *out, const SrcPos *pos, TokenType type, + size_t length) { + out->pos = *pos; + out->type = type; + out->length = length; +} + +static int pprint_character(int c, char *buf, size_t buf_size) { + if (c == EOS) { + return snprintf(buf, buf_size, "EOF"); + } else if (isprint(c)) { + return snprintf(buf, buf_size, "'%c'", (char) c); + } else { + return snprintf(buf, buf_size, "'0x%02Xd'", c); + } +} + +ATTR_FORMAT(3, 4) +static void sprintf_error(TokenStreamError *error, const SrcPos *pos, + const char *restrict fmt, ...) { + if (error) { + error->set = true; + error->pos = *pos; + va_list args; + va_start(args, fmt); + vsnprintf(error->message, sizeof(error->message), fmt, args); + va_end(args); + } +} + +// and now for the actual parser +#define POS (&stream->pos) +#define SET_OUT(p, t, l) set_token(out, (p), (t), (l)) +#define SET_EOF() SET_OUT(POS, TOKEN_EOF, 0) +#define DISCARD_CHAR() popc(stream) +#define DEF_PPRINT(var, c) \ + char var[8]; \ + pprint_character((c), var, sizeof(var)) +#define BYTES_LEFT (stream->src_len - stream->pos.offset) + +static bool read_next_ident(TokenStream *restrict stream, Token *restrict out); +// consume = before using +static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out, + TokenStreamError *restrict error); + +bool token_stream_next(TokenStream *restrict stream, Token *restrict out, + TokenStreamError *restrict error) { + if (error) { + error->set = false; + } +restart: + skip_whitespace(stream); + int c = peekc(stream); + switch (c) { + case EOS: + SET_EOF(); + return true; + case '\\': + case ':': + case '(': + case ')': + SET_OUT(POS, typeof_single_char_token(c), 1); + DISCARD_CHAR(); + return true; + case '=': { + SrcPos start = *POS; + DISCARD_CHAR(); + int next = peekc(stream); + if (next == EOS || is_whitespace(next)) { + SET_OUT(&start, typeof_single_char_token(c), 1); + return true; + } + // note the '=' was already consumed + return read_next_reduce(stream, out, error); + } + case '-': { + SrcPos start = *POS; + popc(stream); // first '-' + int next = popc(stream); + if (next == EOS) { + sprintf_error(error, POS, "unexpected EOF"); + return false; + } else if (next == '-') { + discard_until_newline(stream); + goto restart; + } + SET_OUT(&start, TOKEN_DEFINE, 2); + return true; + } + default: + if (!is_identifier(c)) { + DEF_PPRINT(pp, c); + sprintf_error(error, POS, "expected identifier, got %s", pp); + return false; + } + return read_next_ident(stream, out); + } +} + +static bool read_next_ident(TokenStream *restrict stream, Token *restrict out) { + SrcPos start = *POS; + size_t len = 0; + int c; + while (is_identifier((c = peekc(stream)))) { + popc(stream); + ++len; + } + if (len == 3 && BYTES_LEFT >= 3 + && memcmp(&stream->src[start.offset], "let", 3) == 0) { + SET_OUT(&start, TOKEN_LET, len); + } else if (len == 4 && BYTES_LEFT >= 4 + && memcmp(&stream->src[start.offset], "conf", 4) == 0) { + SET_OUT(&start, TOKEN_CONF, len); + } else if (len == 4 && BYTES_LEFT >= 4 + && memcmp(&stream->src[start.offset], "eval", 4) == 0) { + SET_OUT(&start, TOKEN_EVAL, len); + } else { + SET_OUT(&start, TOKEN_IDENT, len); + } + return true; +} + +static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out, + TokenStreamError *restrict error) { + size_t len = 0; + SrcPos start = *POS; + int c; + while (is_reduce(c = peekc(stream))) { + popc(stream); + ++len; + } + if (c == '>') { + SET_OUT(&start, TOKEN_REDUCE, len); + DISCARD_CHAR(); + return true; + } else { + DEF_PPRINT(pp, c); + sprintf_error(error, POS, "expected '>', got %s", pp); + return false; + } +} diff --git a/parse.h b/parse.h new file mode 100644 index 0000000..e950e0a --- /dev/null +++ b/parse.h @@ -0,0 +1,85 @@ +#ifndef INCLUDED_PARSE_H +#define INCLUDED_PARSE_H + +#include +#include +#include +#include + +typedef struct { + size_t line; + size_t column; + size_t line_offset; // first char of line + size_t offset; +} SrcPos; + +typedef enum { + // keywords + TOKEN_LET, + TOKEN_EVAL, + TOKEN_CONF, + + // punctuation + TOKEN_EQUALS, + TOKEN_BACKSLASH, + TOKEN_COLON, + TOKEN_OPEN_PAREN, + TOKEN_CLOSE_PAREN, + TOKEN_DEFINE, // -> in lambda definitions + + // variable or macro + TOKEN_IDENT, + + // =abc> + TOKEN_REDUCE, + + // eof + TOKEN_EOF, + N_TOKEN_TYPES, +} TokenType; + +const char *token_type_to_string(TokenType type); + +typedef struct { + SrcPos pos; + TokenType type; + size_t length; +} Token; + +typedef struct { + SrcPos pos; + const char *src; + size_t src_len; +} TokenStream; + +typedef struct { + bool set; + SrcPos pos; + char message[64]; +} TokenStreamError; + +inline static void token_stream_init(TokenStream *stream, const char *src, + size_t src_len) { + stream->pos.line = 1; + stream->pos.column = 0; + stream->pos.offset = 0; + stream->pos.line_offset = 0; + stream->src = src; + stream->src_len = src_len; +} + +inline static bool token_stream_is_eof(TokenStream *stream) { + return stream->pos.offset == stream->src_len; +} + +// return true on success, false on error +bool token_stream_next(TokenStream *restrict stream, Token *restrict out, + TokenStreamError *restrict error); +static inline void token_stream_error_clear(TokenStreamError *error) { + error->set = false; +} +static inline bool token_stream_error_set(const TokenStreamError *error) { + return error->set; +} + +#endif diff --git a/term.c b/term.c new file mode 100644 index 0000000..5bd656e --- /dev/null +++ b/term.c @@ -0,0 +1 @@ +#include "term.h" diff --git a/term.h b/term.h new file mode 100644 index 0000000..2f1c437 --- /dev/null +++ b/term.h @@ -0,0 +1,30 @@ +#ifndef INCLUDED_TERM_H +#define INCLUDED_TERM_H + +#include + +typedef enum { + TYPE_VARIABLE, + TYPE_LAMBDA, + TYPE_APPLY, +} LambdaTermType; + +typedef struct _LambdaTerm LambdaTerm; +struct _LambdaTerm { + LambdaTermType type; + union { + struct { + char name; + } v; + struct { + char argument; + LambdaTerm *body; + } l; + struct { + char function; + LambdaTerm *argument; + }; + }; +}; + +#endif diff --git a/test.lc b/test.lc new file mode 100644 index 0000000..6cb204d --- /dev/null +++ b/test.lc @@ -0,0 +1,14 @@ +-- id_0.lc +let id = \x -> x +let zero = \f x -> x + +eval id_zero: + id zero + =d> (\x -> x) (\f x -> x) -- expand definitions + =a> (\z -> z) (\f x -> x) -- alpha rename + =b> (\f x -> x) -- beta reduce + =d> zero -- expand definitions + +eval id_zero_tr: + id zero + =*> zero -- transitive reductions diff --git a/util.h b/util.h new file mode 100644 index 0000000..42bad49 --- /dev/null +++ b/util.h @@ -0,0 +1,14 @@ +#ifndef INCLUDED_MACRO_H +#define INCLUDED_MACRO_H + +#ifndef __has_attribute +# define __has_attribute(x) 0 +#endif + +#if __has_attribute(format) +# define ATTR_FORMAT(...) __attribute__((format(printf, __VA_ARGS__))) +#else +# define ATTR_FORMAT(...) +#endif + +#endif