core: parser: Add parser groundwork

Signed-off-by: Chloe M. <chloe@aptel.org>

4 files changed, 77 insertions, 0 deletions

diff --git a/core/defconf.c b/core/defconf.c
index 4444179..be55708 100644
--- a/core/defconf.c
+++ b/core/defconf.c
@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include "defconf/state.h"
+#include "defconf/parser.h"
 
 /* Globals */
 static char *config_path = NULL;
@@ -24,11 +25,18 @@ static int
 defconf_run(void)
 {
     struct defconf_state state;
+    int error;
 
     if (defconf_state_init(config_path, &state) < 0) {
         return -1;
     }
 
+    /* Begin parsing the config */
+    if ((error = parse_begin(&state)) < 0) {
+        defconf_state_destroy(&state);
+        return error;
+    }
+
     defconf_state_destroy(&state);
     return 0;
 }
diff --git a/core/parser.c b/core/parser.c
new file mode 100644
index 0000000..727d5e1
--- /dev/null
+++ b/core/parser.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2026, Apollo Telephone Laboratories.
+ * Provided under the BSD-3 clause.
+ */
+
+#include "defconf/parser.h"
+#include "defconf/lexer.h"
+#include "defconf/token.h"
+
+/* Symbolic token */
+#define SYMTOK(TOKSTR) \
+    "[" TOKSTR "]"
+
+/* Literal token */
+#define TOKLIT(TOKSTR)  \
+    "'" TOKSTR "'"
+
+/* Safe macro to convert token type to string */
+#define TOKSTR(TT)      \
+    ((TT) >= _TT_MAX)   \
+        ? "bad"         \
+        : toktab[(TT)]
+
+/* Token to string table */
+static const char *toktab[_TT_MAX] = {
+    [TT_NONE]       = SYMTOK("none"),
+    [TT_DEFINE]     = SYMTOK("define"),
+    [TT_TRUE]       = TOKLIT("true"),
+    [TT_FALSE]      = TOKLIT("false"),
+    [TT_INTLIT]     = SYMTOK("int"),
+    [TT_IDENT]      = SYMTOK("ident")
+};
+
+int
+parse_begin(struct defconf_state *state)
+{
+    struct token tok;
+
+    if (state == NULL) {
+        return -1;
+    }
+
+    while (lexer_scan(state, &tok) == 0) {
+        printf("got %s\n", TOKSTR(tok.type));
+    }
+
+    return 0;
+}
diff --git a/head/defconf/parser.h b/head/defconf/parser.h
new file mode 100644
index 0000000..8306cd5
--- /dev/null
+++ b/head/defconf/parser.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2026, Apollo Telephone Laboratories.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef DEFCONF_PARSER_H
+#define DEFCONF_PARSER_H 1
+
+#include "defconf/state.h"
+
+/*
+ * Begin parsing the configuration
+ *
+ * @state:  Defconf state
+ *
+ * Returns zero on success
+ */
+int parse_begin(struct defconf_state *state);
+
+#endif  /* !DEFCONF_PARSER_H */
diff --git a/head/defconf/token.h b/head/defconf/token.h
index e1abd0a..4a69311 100644
--- a/head/defconf/token.h
+++ b/head/defconf/token.h
@@ -16,6 +16,7 @@ typedef enum {
     TT_FALSE,       /* 'false' */
     TT_INTLIT,      /* [0-9]+ */
     TT_IDENT,       /* [ident] */
+    _TT_MAX
 } tt_t;
 
 /*