From ab7d5d484b911f454f35567ed2f1a1a2dac167f7 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Tue, 12 Oct 2021 17:25:08 +0200
Subject: Add new error values

---
 src/bootstrap/errors.c |   8 +++
 src/bootstrap/parser.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 157 insertions(+)
 create mode 100644 src/bootstrap/parser.c

diff --git a/src/bootstrap/errors.c b/src/bootstrap/errors.c
index fcb629a..87752e6 100644
--- a/src/bootstrap/errors.c
+++ b/src/bootstrap/errors.c
@@ -7,6 +7,10 @@ typedef enum ErrorType {
 typedef enum ErrorValue {
     ERR_UNKNOWN = 0,
     ERR_UNMATCHED_STRING,
+    ERR_UNBALANCED_PAREN,
+    ERR_NOT_IMPLEMENTED,
+    ERR_EOF_REACHED,
+    ERR_UNKNOWN_TOKEN,
 } ErrorValue;
 
 typedef struct Error {
@@ -19,6 +23,10 @@ typedef struct Error {
 static const char* error_msgs[] = {
     [ERR_UNKNOWN] = "error: something unexpected happened",
     [ERR_UNMATCHED_STRING] = "error: unmatched string delimiter",
+    [ERR_UNBALANCED_PAREN] = "error: unbalanced parentheses",
+    [ERR_NOT_IMPLEMENTED] = "error: not implemented",
+    [ERR_EOF_REACHED] = "error: EOF reached",
+    [ERR_UNKNOWN_TOKEN] = "error: unknown token",
 };
 
 #define ERR_MAX_NUMBER 16
diff --git a/src/bootstrap/parser.c b/src/bootstrap/parser.c
new file mode 100644
index 0000000..c84c6c6
--- /dev/null
+++ b/src/bootstrap/parser.c
@@ -0,0 +1,149 @@
+typedef struct Visitor {
+    Tokens tokens;
+    size_t current;
+} Visitor;
+
+Token
+peek_token(const Visitor *visitor) {
+    return visitor->tokens.buf[visitor->current];
+}
+
+Token
+next_token(Visitor *visitor) {
+    return visitor->tokens.buf[visitor->current++];
+}
+
+bool
+has_next_token(const Visitor *visitor) {
+    return visitor->current < visitor->tokens.size;
+}
+
+Object *
+parse_fixnum(Token tok) {
+    ssize_t num = 0;
+    int sign = 1;
+    for (size_t i = 0; i < tok.value.n; i++) {
+        char c = tok.value.start[i];
+        if (c == '-') {
+            sign = -1;
+            continue;
+        }
+        num = num * 10 + (c - '0');
+    }
+    return make_fixnum(num * sign);
+}
+
+Object * parse_tree(Visitor *vs);
+
+Object *
+parse_list(Visitor *vs) {
+    Token tok = peek_token(vs);
+    if (tok.type == TOKEN_EOF) {
+        error_push((Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_UNBALANCED_PAREN,
+            .line = tok.line,
+            .col = tok.column,
+        });
+        return obj_err;
+    }
+    Object *next_obj = parse_tree(vs);
+    if (next_obj == obj_err) {
+        return obj_err;
+    }
+    Object *root = make_pair(next_obj, obj_nil);
+    Object *list = root;
+    while (has_next_token(vs)) {
+        Token tok = peek_token(vs);
+        if (tok.type == TOKEN_RPAREN) {
+            next_token(vs);
+            break;
+        }
+        if (tok.type == TOKEN_EOF) {
+            error_push((Error){
+                .type = ERR_TYPE_PARSER,
+                .value = ERR_UNBALANCED_PAREN,
+                .line = tok.line,
+                .col = tok.column,
+            });
+            free_objects(root);
+            return obj_err;
+        }
+        next_obj = parse_tree(vs);
+        if (next_obj == obj_err) {
+            free_objects(root);
+            return obj_err;
+        }
+        list->cdr = make_pair(next_obj, obj_nil);
+        list = list->cdr;
+    }
+    return root;
+}
+
+Object *
+parse_tree(Visitor *vs) {
+    Token tok = next_token(vs);
+    switch (tok.type) {
+        case TOKEN_FIXNUM: {
+            return parse_fixnum(tok);
+        } break;
+        case TOKEN_TRUE: {
+            return obj_true;
+        } break;
+        case TOKEN_FALSE: {
+            return obj_false;
+        } break;
+        case TOKEN_RPAREN: {
+            error_push((Error){
+                .type = ERR_TYPE_PARSER,
+                .value = ERR_UNBALANCED_PAREN,
+                .line = tok.line,
+                .col = tok.column,
+            });
+            return obj_err;
+        } break;
+        case TOKEN_QUOTE: {
+            // TODO: Implement.
+            error_push((Error){
+                .type = ERR_TYPE_PARSER,
+                .value = ERR_NOT_IMPLEMENTED,
+                .line = tok.line,
+                .col = tok.column,
+            });
+            return obj_err;
+        } break;
+        case TOKEN_LPAREN: {
+            return parse_list(vs);
+        } break;
+        case TOKEN_STRING: {
+            Object *obj = make_string();
+            append_string(obj, tok.value);
+            return obj;
+        } break;
+        case TOKEN_SYMBOL: {
+            return make_symbol(tok.value);
+        } break;
+        case TOKEN_EOF: {
+            error_push((Error){
+                .type = ERR_TYPE_PARSER,
+                .value = ERR_EOF_REACHED,
+                .line = tok.line,
+                .col = tok.column,
+            });
+            return obj_err;
+        } break;
+        case TOKEN_NIL: {
+            return obj_nil;
+        } break;
+        default: {
+            break;
+        } break;
+    }
+    error_push((Error){
+        .type = ERR_TYPE_PARSER,
+        .value = ERR_EOF_REACHED,
+        .line = tok.line,
+        .col = tok.column,
+    });
+    return obj_err;
+}
-- 
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