Initial commit: Basic found.

- I use flex and bison for lexical and syntax analysis, and main c
  to run command
- basic CFG built to deal with easy command without redirecion (
  it's written but have serious problem)
- it can now run command one by one, and use \ to change line
  without ending the command.

Fighting forward!

6 files changed, 163 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..66c7e33
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,8 @@
+*
+!*.*
+!*/*
+!Makefile
+*.o
+*.tab*
+lex.yy.c
+*.output
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..8410a24
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,32 @@
+CC = gcc
+FLEX = flex
+BISON = bison
+
+CFILES = $(shell find . -name "*.c")
+OBJS = $(CFILES:.c=.o)
+LFILE = $(wildcard *.l)
+YFILE = $(wildcard *.y)
+LFC = ./lex.yy.c
+YFC = ./syntax.tab.c
+LFO = $(LFC:.c=.o)
+YFO = $(YFC:.c=.o)
+
+bcsh: syntax $(filter-out $(LFO),$(OBJS))
+        $(CC) -g -o bcsh $(filter-out $(LFO),$(OBJS)) -lfl
+
+syntax: lexical syntax-c
+        $(CC) -c $(YFC) -o $(YFO)
+
+lexical: $(LFILE)
+        $(FLEX) -o $(LFC) $(LFILE)
+
+syntax-c: $(YFILE)
+        $(BISON) -o $(YFC) -d -v $(YFILE) -Wcounterexamples
+
+-include $(patsubst %.o, %.d, $(OBJS))
+
+clean:
+        rm -f bcsh lex.yy.c syntax.tab.c syntax.tab.h syntax.output
+        rm -f $(OBJS) $(OBJS:.o=.d)
+        rm -f $(LFC) $(YFC) $(YFC:.c=.h)
+        rm -f *~
\ No newline at end of file
diff --git a/bcsh.c b/bcsh.c
new file mode 100644
index 0000000..ca83402
--- /dev/null
+++ b/bcsh.c
@@ -0,0 +1,10 @@
+#include "cmd.h"
+
+extern int yyparse();
+
+int main(int argc, char **argv) {
+    while (true) {
+        yyparse();
+    }
+    return 0;
+}
\ No newline at end of file
diff --git a/cmd.h b/cmd.h
new file mode 100644
index 0000000..adf03c7
--- /dev/null
+++ b/cmd.h
@@ -0,0 +1,30 @@
+#ifndef CMD_H
+#define CMD_H
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef enum {
+    CMD_TYPE_NORMAL,
+    CMD_TYPE_PIPE,
+    CMD_TYPE_AND,
+    CMD_TYPE_OR,
+    // add more command types as needed
+} CommandType;
+
+typedef struct Command {
+    CommandType type; // the type of the command
+    char **args;      // an array of strings for the arguments of the command
+    struct Command *left;  // a pointer to the left sub-command
+    struct Command *right; // a pointer to the right sub-command
+    char *redirect_in;  // the file name for input redirection, or NULL if there
+                        // is no input redirection
+    char *redirect_out; // the file name for output redirection, or NULL if
+                        // there is no output redirection
+    char *append_out; // the file name for output appending, or NULL if there is
+                      // no output appending
+    // add more fields as needed
+} Command;
+
+#endif
\ No newline at end of file
diff --git a/lex.l b/lex.l
new file mode 100644
index 0000000..036d58e
--- /dev/null
+++ b/lex.l
@@ -0,0 +1,33 @@
+%{
+#include "syntax.tab.h"  // Bison 生成的头文件
+
+void yyerror(const char *s);
+%}
+
+%option noyywrap
+
+%%
+
+[\t ]+                 { /* Ignore whitespace */ }
+"\n"                   { printf("new line\n");return NEWLINE; }
+"\\\n"                 { printf("> "); }
+">>"                   { return APPEND_OUT; }
+"<<"                   { return HEREDOC; }
+">"                    { return REDIRECT_OUT; }
+"<"                    { return REDIRECT_IN; }
+">>&"                  { return APPEND_OUTPUT_ERR; }
+">&"                   { return REDIRECT_OUTPUT_ERR; }
+"|"                    { return PIPE; }
+"&&"                   { return AND; }
+"||"                   { return OR; }
+"&"                    { return BACKGROUND; }
+\"(\\.|[^\"])*\"       { yylval.str = strdup(yytext); return STRING; }
+[a-zA-Z0-9_\-\/.]+     { yylval.str = strdup(yytext); return WORD; }
+
+
+%%
+
+void yyerror(const char *s)
+{
+    fprintf(stderr, "error: %s\n", s);
+}
diff --git a/syntax.y b/syntax.y
new file mode 100644
index 0000000..aa0df71
--- /dev/null
+++ b/syntax.y
@@ -0,0 +1,50 @@
+%{
+#include "lex.yy.c"
+#include "cmd.h"
+
+%}
+
+%union {
+    char *str;
+}
+
+%token <str> WORD STRING
+%token NEWLINE CONTINUATION APPEND_OUT REDIRECT_OUT REDIRECT_IN APPEND_OUTPUT_ERR REDIRECT_OUTPUT_ERR PIPE AND OR BACKGROUND HEREDOC UNKNOWN
+
+%%
+
+line:
+    command NEWLINE { printf("Parsed a command.\n"); }
+    | NEWLINE { /* empty line */ }
+    ;
+
+command:
+    part {printf("PART\n"); }
+    | part separator command { printf("COMMAND\n"); }
+    | part REDIRECT_OUT WORD tail { printf("REDIRECT_OUT: %s\n", $3); free($3); }
+    | part REDIRECT_IN WORD tail { printf("REDIRECT_IN: %s\n", $3); free($3); }
+    | part HEREDOC WORD tail { printf("HEREDOC: %s\n", $3); free($3); }
+    | part BACKGROUND { printf("BACKGROUND\n"); }
+    ;
+
+tail:
+    part
+    | part REDIRECT_OUT WORD tail { printf("REDIRECT_OUT: %s\n", $3); free($3); }
+    | part REDIRECT_IN WORD tail { printf("REDIRECT_IN: %s\n", $3); free($3); }
+    | part HEREDOC WORD tail { printf("HEREDOC: %s\n", $3); free($3); }
+    ;
+
+part:
+    part WORD { printf("WORD: %s\n", $2); free($2); }
+    | part STRING { printf("STRING: %s\n", $2); free($2); }
+    | WORD { printf("WORD: %s\n", $1); free($1); }
+    | STRING { printf("STRING: %s\n", $1); free($1); }
+    ;
+
+separator:
+    PIPE { printf("PIPE\n"); }
+    | AND { printf("AND\n"); }
+    | OR { printf("OR\n"); }
+    ;
+
+%%
\ No newline at end of file