refactor(lex_parser): 移除旧的词法解析器实现并更新依赖

移除了 libs/lex_parser 目录下的所有头文件和源文件，包括：
- lex_parser.h 和 lex_parser.c 核心解析功能
- 所有测试文件（test_char.c, test_identifier.c, test_number.c,
  test_skip_block_comment.c, test_skip_line.c, test_string.c）

更新了 lexer 模块的依赖配置，将 lex_parser 替换为 sstream，
同时更新了 lexer.h 中的相关包含头文件和数据结构定义，
简化了 scc_lexer_t 结构体的字段。

libs/sstream/src/main.c

@@ -0,0 +1,51 @@
+#include "scc_sstream.h"
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+    const char *filename = (argc > 1) ? argv[1] : __FILE__; // 默认读取自身
+    scc_sstream_t stream;
+    scc_sstream_ring_t *ring;
+
+    // 初始化
+    if (scc_sstream_init(&stream, filename, 16) != 0) {
+        fprintf(stderr, "Failed to initialize stream for %s\n", filename);
+        return 1;
+    }
+    ring = scc_sstream_ref_ring(&stream);
+    Assert(ring != null);
+
+    printf("Reading file: %s\n", filename);
+
+    scc_sstream_char_t elem;
+    cbool ok;
+    int char_count = 0;
+    int line_count = 0;
+
+    // 循环读取所有字符
+    while (1) {
+        scc_ring_next_consume(*ring, elem, ok);
+        if (!ok)
+            break; // 文件结束或错误
+
+        char_count++;
+        if (elem.character == '\n')
+            line_count++;
+
+        // 打印前 200 个字符的位置信息（避免刷屏）
+        if (char_count <= 200) {
+            printf("char[%d]: '%c' (line %zu, col %zu)\n", char_count,
+                   elem.character == '\n' ? ' '
+                                          : elem.character, // 换行符显示为空格
+                   elem.pos.line, elem.pos.col);
+        }
+    }
+
+    printf("\nSummary:\n");
+    printf("  Total characters: %d\n", char_count);
+    printf("  Total lines: %d\n", line_count);
+
+    // 释放资源
+    scc_sstream_drop_ring(ring);
+    scc_sstream_drop(&stream);
+    return 0;
+}

libs/sstream/src/scc_sstream.c

@@ -0,0 +1,145 @@
+#include <scc_sstream.h>
+
+// 内部扫描函数：从指定位置扫描下一个有效字符
+static int sstream_scan_at(scc_sstream_t *stream, scc_pos_t scan_pos,
+                           scc_pos_t *out_char_pos, scc_pos_t *out_next_pos) {
+    while (1) {
+        if (scan_pos.offset >= stream->len)
+            return -1; // EOF
+
+        scc_pos_t start = scan_pos;
+        char c = stream->src[scan_pos.offset];
+
+        // 处理反斜杠换行
+        if (c == '\\') {
+            usize next_off = scan_pos.offset + 1;
+            if (next_off < stream->len) {
+                char n = stream->src[next_off];
+                if (n == '\n') {
+                    // 跳过 '\' 和 '\n'
+                    scan_pos.offset += 2;
+                    scan_pos.line++;
+                    scan_pos.col = 1;
+                    continue;
+                } else if (n == '\r' && next_off + 1 < stream->len &&
+                           stream->src[next_off + 1] == '\n') {
+                    // 跳过 '\' + '\r' + '\n'
+                    scan_pos.offset += 3;
+                    scan_pos.line++;
+                    scan_pos.col = 1;
+                    continue;
+                }
+            }
+        }
+
+        // 处理 \r\n 转换为 \n
+        if (c == '\r') {
+            usize next_off = scan_pos.offset + 1;
+            if (next_off < stream->len && stream->src[next_off] == '\n') {
+                if (out_char_pos)
+                    *out_char_pos = start;
+                // 下一个位置：偏移+2，行+1，列=1
+                scan_pos.offset += 2;
+                scan_pos.line++;
+                scan_pos.col = 1;
+                if (out_next_pos)
+                    *out_next_pos = scan_pos;
+                return '\n';
+            }
+        }
+
+        // 普通字符（包括单独的 '\n'、'\r' 等）
+        if (out_char_pos)
+            *out_char_pos = start;
+        // 计算下一个位置
+        scan_pos.offset++;
+        if (c == '\n') {
+            scan_pos.line++;
+            scan_pos.col = 1;
+        } else {
+            scan_pos.col++;
+        }
+        if (out_next_pos)
+            *out_next_pos = scan_pos;
+        return c;
+    }
+}
+
+// 环形缓冲区填充回调（通过 userdata 获取流对象）
+static cbool fill_func(scc_sstream_char_t *out, void *userdata) {
+    scc_sstream_t *stream = (scc_sstream_t *)userdata;
+    if (stream->fill_pos.offset >= stream->len)
+        return false; // 已到文件尾
+
+    int ch = sstream_scan_at(stream, stream->fill_pos, &out->pos,
+                             &(stream->fill_pos));
+    if (ch == -1)
+        return false;
+    out->character = ch;
+    return true;
+}
+
+int scc_sstream_init(scc_sstream_t *stream, const char *fname, int ring_size) {
+    Assert(stream != null && fname != null);
+    scc_file_t file = scc_fopen(fname, SCC_FILE_READ);
+    usize fsize = scc_fsize(file);
+    if (fsize == 0) {
+        LOG_WARN("file size is 0");
+        scc_fclose(file);
+        return 0;
+    }
+    char *buffer = (char *)scc_malloc(fsize);
+    scc_memset(buffer, 0, fsize);
+    usize read_ret = scc_fread(file, buffer, fsize);
+    Assert(read_ret == fsize); /* read bytes assert it */
+    scc_fclose(file);
+
+    scc_sstream_init_by_buffer(stream, buffer, read_ret, 1, ring_size);
+    stream->fname = fname;
+    stream->fill_pos.name = stream->fname;
+    return 0;
+}
+
+int scc_sstream_init_by_buffer(scc_sstream_t *stream, const char *buffer,
+                               usize len, int owned, int ring_size) {
+    stream->fname = "<buffer>";
+    stream->fill_pos = scc_pos_create();
+    stream->fill_pos.name = stream->fname;
+    stream->src = buffer;
+    stream->len = len;
+    stream->owned_src = owned;
+
+    scc_ring_init(stream->ring, ring_size <= 0 ? 64 : ring_size, fill_func,
+                  stream);
+    stream->used = 0;
+    return 0;
+}
+
+scc_sstream_ring_t *scc_sstream_ref_ring(scc_sstream_t *stream) {
+    Assert(stream != null);
+    stream->used++;
+    return &stream->ring;
+}
+
+void scc_sstream_drop_ring(scc_sstream_ring_t *ring) {
+    Assert(ring != null && ring->userdata != null);
+    scc_sstream_t *stream = (scc_sstream_t *)ring->userdata;
+    if (stream->used > 0) {
+        stream->used--;
+    } else {
+        LOG_WARN("double drop sstream ring");
+    }
+}
+
+void scc_sstream_drop(scc_sstream_t *stream) {
+    Assert(stream != null);
+    if (stream->used) {
+        LOG_FATAL("drop sstream must be drop ring before ref [%d]",
+                  stream->used);
+    }
+    if (stream->src && stream->owned_src) {
+        scc_free((void *)stream->src);
+        stream->src = null;
+    }
+    scc_ring_free(stream->ring);
+}