Some work

Makefile

@@ -5,7 +5,7 @@ CFLAGS=-std=c11 -D_FILE_OFFSET_BITS=64 -D_POSIX_C_SOURCE=200112L -Wall -Wextra $
 LD=gcc
 LDFLAGS=$(DEBUG_FLAGS)
 
-lambda: main.o token.o lc.o
+lambda: main.o token.o lc.o util.o
 	$(LD) $(LDFLAGS) -o $@ $^
 
 %.o: %.c
@@ -19,4 +19,5 @@ clean:
 # Dependencies
 main.o: token.h lc.h
 token.o: token.h util.h
-lc.o: lc.h token.h
+lc.o: lc.h token.h util.h
+util.o: util.h

lc.c

@@ -1 +1,144 @@
 #include "lc.h"
+
+#include "util.h"
+
+#include <stdarg.h>
+#include <stdbool.h>
+
+static LambdaTerm *make_variable(char *name, size_t name_len) {
+    LambdaTerm *term = malloc_safe(sizeof(LambdaTerm));
+    term->type = TYPE_VARIABLE;
+    term->v.name = name;
+    term->v.name_len = name_len;
+    return term;
+}
+
+static LambdaTerm *make_lambda(char *arg, size_t arg_len, LambdaTerm *body) {
+    LambdaTerm *term = malloc_safe(sizeof(LambdaTerm));
+    term->type = TYPE_LAMBDA;
+    term->l.arg = arg;
+    term->l.arg_len = arg_len;
+    term->l.body = body;
+    return term;
+}
+
+static LambdaTerm *make_apply(LambdaTerm *func, LambdaTerm *arg) {
+    LambdaTerm *term = malloc_safe(sizeof(LambdaTerm));
+    term->type = TYPE_APPLY;
+    term->a.func = func;
+    term->a.arg = arg;
+    return term;
+}
+
+static bool is_lambda_term_token(const Token *tok) {
+    switch (tok->type) {
+    case TOKEN_BACKSLASH:
+    case TOKEN_OPEN_PAREN:
+    case TOKEN_CLOSE_PAREN:
+    case TOKEN_IDENT:
+        return true;
+    case TOKEN_LET:
+    case TOKEN_EVAL:
+    case TOKEN_CONF:
+    case TOKEN_EQUALS:
+    case TOKEN_COLON:
+    case TOKEN_DEFINE:
+    case TOKEN_REDUCE:
+    case TOKEN_EOF:
+        return false;
+    default:
+        abort();
+    }
+}
+
+enum OperatorType {
+    OPER_APPLY,
+    OPER_DEFINE,
+};
+
+struct OperatorStack {
+    struct OperatorStack *next;
+    Token src;
+    enum OperatorType type;
+};
+
+static struct OperatorStack *push_oper(struct OperatorStack *restrict stack,
+                                       const Token *restrict src,
+                                       enum OperatorType type) {
+    struct OperatorStack *new = malloc_safe(sizeof(struct OperatorStack));
+    new->next = stack;
+    new->src = *src;
+    new->type = type;
+    return new;
+}
+
+enum OperandType {
+    OPAND_TERM,
+    OPAND_OPEN_PAREN,
+    OPAND_DEF_BEGIN,
+};
+
+struct OperandStack {
+    struct OperandStack *next;
+    Token src;
+    enum OperandType type;
+    LambdaTerm *term;
+};
+
+static struct OperandStack *push_opand(struct OperandStack *restrict stack,
+                                       const Token *restrict src,
+                                       enum OperandType type, ...) {
+    struct OperandStack *new = malloc_safe(sizeof(struct OperandStack));
+    new->next = stack;
+    new->src = *src;
+    new->type = type;
+    if (type == OPAND_TERM) {
+        va_list args;
+        va_start(args, type);
+        new->term = va_arg(args, LambdaTerm *);
+        va_end(args);
+    }
+    return new;
+}
+
+static void apply_one(struct OperatorStack **oper_stack,
+                      struct OperandStack **opand_stack,
+                      ParseError *restrict err_out) {
+    if (!*oper_stack) {
+        abort();
+    } else if () {
+    }
+}
+
+LambdaTerm *read_lambda_term(TokenStream *restrict stream,
+                             ParseError *restrict err_out) {
+    ParseError backup_err;
+    if (!err_out) {
+        err_out = &backup_err;
+    }
+    struct OperatorStack *oper_stack = NULL;
+    struct OperandStack *opand_stack = NULL;
+    Token tok;
+    while (true) {
+        if (!token_stream_peek(stream, &tok, err_out)) {
+            return false;
+        } else if (!is_lambda_term_token(&tok)) {
+            break;
+        }
+        token_stream_discard(stream, NULL);
+        switch (tok.type) {
+        case TOKEN_OPEN_PAREN:
+            opand_stack = push_opand(opand_stack, OPAND_OPEN_PAREN);
+            break;
+        case TOKEN_BACKSLASH:
+            opand_stack = push_opand(opand_stack, OPAND_DEF_BEGIN);
+            break;
+        case TOKEN_CLOSE_PAREN:
+        case TOKEN_IDENT:
+        case TOKEN_DEFINE:
+            break;
+        default:
+            abort();
+        }
+    }
+}

lc.h

@@ -1,6 +1,8 @@
 #ifndef INCLUDED_TERM_H
 #define INCLUDED_TERM_H
 
+#include "token.h"
+
 #include <stddef.h>
 
 typedef enum {
@@ -14,17 +16,22 @@ struct _LambdaTerm {
     LambdaTermType type;
     union {
         struct {
-            char name;
+            char *name;
+            size_t name_len;
         } v;
         struct {
-            char argument;
+            char *arg;
+            size_t arg_len;
             LambdaTerm *body;
         } l;
         struct {
-            char function;
-            LambdaTerm *argument;
-        };
+            LambdaTerm *func;
+            LambdaTerm *arg;
+        } a;
     };
 };
 
+LambdaTerm *read_lambda_term(TokenStream *restrict stream,
+                             ParseError *restrict err_out);
+
 #endif

token.c

@@ -136,11 +136,32 @@ static bool read_next_ident(TokenStream *restrict stream, Token *restrict out);
 static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out,
                              ParseError *restrict error);
 
+bool token_stream_peek(TokenStream *restrict stream, Token *restrict out,
+                       ParseError *restrict error) {
+    if (error) {
+        error->set = false;
+    }
+    if (!stream->has_buffer) {
+        bool res = token_stream_next(stream, &stream->buffer, error);
+        if (!res) {
+            return false;
+        }
+        stream->has_buffer = true;
+    }
+    *out = stream->buffer;
+    return true;
+}
+
 bool token_stream_next(TokenStream *restrict stream, Token *restrict out,
                        ParseError *restrict error) {
     if (error) {
         error->set = false;
     }
+    if (stream->has_buffer) {
+        stream->has_buffer = false;
+        *out = stream->buffer;
+        return true;
+    }
 restart:
     skip_whitespace(stream);
     int c = peekc(stream);
@@ -232,3 +253,16 @@ static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out,
         return false;
     }
 }
+
+bool token_stream_discard(TokenStream *restrict stream,
+                          ParseError *restrict error) {
+    if (stream->has_buffer) {
+        stream->has_buffer = false;
+        if (error) {
+            error->set = false;
+        }
+        return true;
+    }
+    Token tok;
+    return token_stream_next(stream, &tok, error);
+}

token.h

@@ -50,6 +50,9 @@ typedef struct {
     SrcPos pos;
     const char *src;
     size_t src_len;
+
+    bool has_buffer;
+    Token buffer;
 } TokenStream;
 
 typedef struct {
@@ -66,6 +69,7 @@ inline static void token_stream_init(TokenStream *stream, const char *src,
     stream->pos.line_offset = 0;
     stream->src = src;
     stream->src_len = src_len;
+    stream->has_buffer = false;
 }
 
 inline static bool token_stream_is_eof(TokenStream *stream) {
@@ -73,8 +77,13 @@ inline static bool token_stream_is_eof(TokenStream *stream) {
 }
 
 // return true on success, false on error
+bool token_stream_peek(TokenStream *restrict stream, Token *restrict out,
+                       ParseError *restrict error);
 bool token_stream_next(TokenStream *restrict stream, Token *restrict out,
                        ParseError *restrict error);
+bool token_stream_discard(TokenStream *restrict stream,
+                          ParseError *restrict error);
+
 static inline void parse_error_clear(ParseError *error) {
     error->set = false;
 }

util.c

@@ -0,0 +1,13 @@
+#include "util.h"
+
+#include <stdio.h>
+
+void *malloc_safe(size_t size) {
+    void *ptr = malloc(size);
+    if (!ptr && size) {
+        static char message[] = "out of memory!\n";
+        fwrite(message, 1, sizeof(message) - 1, stdout);
+        abort();
+    }
+    return ptr;
+}

util.h

@@ -11,4 +11,8 @@
 #    define ATTR_FORMAT(...)
 #endif
 
+#include <stdlib.h>
+
+void *malloc_safe(size_t size);
+
 #endif