#!/bin/bash

# If this file has already been sourced, just return
test $(SPECIALFORMS_LET_SH+true)TODO  && return
declare -g SPECIALFORMS_LET_SH = 'true'

source ${BASH_SOURCE%/*}/common.sh
source ${BASH_SOURCE%/*}/test.sh
source ${BASH_SOURCE%/*}/specialforms.sh

#
# LET
# 
# The inits are evaluated in the current environment (in some unspecified order), 
# the variables are bound to fresh locations holding the results, the expressions
# are evaluated sequentially in the extended environment, and the value of the
# last expression is returned. Each binding of a variable has the expressions as
# its region. 
#
# (let ((x 2) (y 3))
#      (* x y))     
#

proc evaluator::specialforms::letTODO  {
    declare env = $(1)TODO 
    declare functionName = $(2)TODO  # let
    declare args = $(3) # list of <formal args list>, <expression>,...,<expression>

    variable::LinkedList::length $argsTODO  ; declare -i length = $(RESULT)
    if [[ $length < 2 ]] {
        stderr "usage: (let <bindings> <expr 1> .. <expr N>)"
        exit 1
    }

    variable::LinkedList::first $argsTODO  ; declare bindings = $(RESULT)
    variable::LinkedList::rest $argsTODO  ; declare expressions = $(RESULT)

    # set values
    environment::pushScope $envTODO  ; declare runningEnv = $(RESULT)TODO 
    declare thisBinding = '', thisKey = '', thisValue = '', thisResult = ''
    while ! variable::LinkedList::isEmpty_c "${bindings}"  {
        variable::LinkedList::first $(bindings) ; global thisBinding := $(RESULT)
        variable::LinkedList::rest $(bindings) ; global bindings := $(RESULT)

        variable::LinkedList::length $(thisBinding)
        if [[ "${RESULT}" != 2 ]] {
            stderr "let binding must have exactly 2 elements"
        }
        
        variable::LinkedList::index $(thisBinding) 0 ; global thisKey := $(RESULT)
        variable::LinkedList::index $(thisBinding) 1 ; global thisValue := $(RESULT)
        evaluator::eval $env $thisValue
        environment::setVariable $(runningEnv) $thisKey $RESULT
    }TODO 

    # evaluate expressions
    declare currentSexp = '', currentResult = ''
    while ! variable::LinkedList::isEmpty_c "${expressions}"  {
        variable::LinkedList::first $(expressions) ; global currentSexp := $(RESULT)
        variable::LinkedList::rest $(expressions) ; global expressions := $(RESULT)
        evaluator::eval $runningEnv $currentSexp
        global currentResult := $(RESULT)
    }
    global RESULT := $(currentResult)
}



# 
# ======================================================
if test $0 != $BASH_SOURCE {
    return
}





assert::report

if test $(1+isset) && test $1 == "debug" { 
    variable::printMetadata
}

(CommandList
  children: [
    (AndOr
      children: [
        (C {(Lit_Other "[")} 
          {
            (BracedVarSub
              token: <VSub_Name SPECIALFORMS_LET_SH>
              suffix_op: (StringUnary op_id:VTest_Plus arg_word:{(true)})
              spids: [9 13]
            )
          } {(Lit_Other "]")}
        )
        (ControlFlow token:<ControlFlow_Return return>)
      ]
      op_id: Op_DAmp
    )
    (Assignment
      keyword: Assign_Declare
      flags: ["'-g'"]
      pairs: [(assign_pair lhs:(LhsName name:SPECIALFORMS_LET_SH) op:Equal rhs:{(true)} spids:[25])]
      spids: [21]
    )
    (C {(.)} 
      {
        (BracedVarSub
          token: <VSub_Name BASH_SOURCE>
          suffix_op: (StringUnary op_id:VOp1_Percent arg_word:{(Lit_Slash /) ("*")})
          spids: [31 36]
        ) (/common.sh)
      }
    )
    (C {(.)} 
      {
        (BracedVarSub
          token: <VSub_Name BASH_SOURCE>
          suffix_op: (StringUnary op_id:VOp1_Percent arg_word:{(Lit_Slash /) ("*")})
          spids: [41 46]
        ) (/test.sh)
      }
    )
    (C {(.)} 
      {
        (BracedVarSub
          token: <VSub_Name BASH_SOURCE>
          suffix_op: (StringUnary op_id:VOp1_Percent arg_word:{(Lit_Slash /) ("*")})
          spids: [51 56]
        ) (/specialforms.sh)
      }
    )
    (FuncDef
      name: "evaluator::specialforms::let"
      body: 
        (BraceGroup
          children: [
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:env)
                  op: Equal
                  rhs: {(DQ (${ VSub_Number 1))}
                  spids: [114]
                )
              ]
              spids: [112]
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:functionName)
                  op: Equal
                  rhs: {(DQ (${ VSub_Number 2))}
                  spids: [124]
                )
              ]
              spids: [122]
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:args)
                  op: Equal
                  rhs: {(DQ (${ VSub_Number 3))}
                  spids: [137]
                )
              ]
              spids: [135]
            )
            (Sentence
              child: 
                (C 
                  {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                    (Lit_Other ":") (length)
                  } {($ VSub_Name "$args")}
                )
              terminator: <Op_Semi ";">
            )
            (Assignment
              keyword: Assign_Declare
              flags: ["'-i'"]
              pairs: [
                (assign_pair
                  lhs: (LhsName name:length)
                  op: Equal
                  rhs: {(DQ (${ VSub_Name RESULT))}
                  spids: [165]
                )
              ]
              spids: [161]
            )
            (If
              arms: [
                (if_arm
                  cond: [
                    (Sentence
                      child: 
                        (DBracket
                          expr: 
                            (BoolBinary
                              op_id: Redir_Less
                              left: {($ VSub_Name "$length")}
                              right: {(2)}
                            )
                        )
                      terminator: <Op_Semi ";">
                    )
                  ]
                  action: [
                    (C {(stderr)} {(DQ ("usage: (let <bindings> <expr 1> .. <expr N>)"))})
                    (C {(exit)} {(1)})
                  ]
                  spids: [-1 186]
                )
              ]
              spids: [-1 201]
            )
            (Sentence
              child: 
                (C 
                  {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                    (Lit_Other ":") (first)
                  } {($ VSub_Name "$args")}
                )
              terminator: <Op_Semi ";">
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:bindings)
                  op: Equal
                  rhs: {(${ VSub_Name RESULT)}
                  spids: [219]
                )
              ]
              spids: [217]
            )
            (Sentence
              child: 
                (C 
                  {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                    (Lit_Other ":") (rest)
                  } {($ VSub_Name "$args")}
                )
              terminator: <Op_Semi ";">
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:expressions)
                  op: Equal
                  rhs: {(${ VSub_Name RESULT)}
                  spids: [239]
                )
              ]
              spids: [237]
            )
            (Sentence
              child: 
                (C {(environment) (Lit_Other ":") (Lit_Other ":") (pushScope)} {($ VSub_Name "$env")})
              terminator: <Op_Semi ";">
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair
                  lhs: (LhsName name:runningEnv)
                  op: Equal
                  rhs: {(DQ (${ VSub_Name RESULT))}
                  spids: [261]
                )
              ]
              spids: [259]
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair lhs:(LhsName name:thisBinding) op:Equal spids:[271])
                (assign_pair lhs:(LhsName name:thisKey) op:Equal spids:[273])
                (assign_pair lhs:(LhsName name:thisValue) op:Equal spids:[275])
                (assign_pair lhs:(LhsName name:thisResult) op:Equal spids:[277])
              ]
              spids: [269]
            )
            (While
              cond: [
                (Sentence
                  child: 
                    (Pipeline
                      children: [
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (isEmpty_c)
                          } {(DQ (${ VSub_Name bindings))}
                        )
                      ]
                      negated: True
                    )
                  terminator: <Op_Semi ";">
                )
              ]
              body: 
                (DoGroup
                  children: [
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (first)
                          } {(DQ (${ VSub_Name bindings))}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:thisBinding)
                          op: Equal
                          rhs: {(DQ (${ VSub_Name RESULT))}
                          spids: [319]
                        )
                      ]
                      spids: [319]
                    )
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (rest)
                          } {(DQ (${ VSub_Name bindings))}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:bindings)
                          op: Equal
                          rhs: {(DQ (${ VSub_Name RESULT))}
                          spids: [343]
                        )
                      ]
                      spids: [343]
                    )
                    (C 
                      {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                        (Lit_Other ":") (length)
                      } {(DQ (${ VSub_Name thisBinding))}
                    )
                    (If
                      arms: [
                        (if_arm
                          cond: [
                            (Sentence
                              child: 
                                (DBracket
                                  expr: 
                                    (BoolBinary
                                      op_id: BoolBinary_GlobNEqual
                                      left: {(DQ (${ VSub_Name RESULT))}
                                      right: {(2)}
                                    )
                                )
                              terminator: <Op_Semi ";">
                            )
                          ]
                          action: [(C {(stderr)} {(DQ ("let binding must have exactly 2 elements"))})]
                          spids: [-1 384]
                        )
                      ]
                      spids: [-1 394]
                    )
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (index)
                          } {(DQ (${ VSub_Name thisBinding))} {(0)}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:thisKey)
                          op: Equal
                          rhs: {(DQ (${ VSub_Name RESULT))}
                          spids: [417]
                        )
                      ]
                      spids: [417]
                    )
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (index)
                          } {(DQ (${ VSub_Name thisBinding))} {(1)}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:thisValue)
                          op: Equal
                          rhs: {(DQ (${ VSub_Name RESULT))}
                          spids: [443]
                        )
                      ]
                      spids: [443]
                    )
                    (C {(evaluator) (Lit_Other ":") (Lit_Other ":") (eval)} {($ VSub_Name "$env")} 
                      {($ VSub_Name "$thisValue")}
                    )
                    (C {(environment) (Lit_Other ":") (Lit_Other ":") (setVariable)} 
                      {(DQ (${ VSub_Name runningEnv))} {($ VSub_Name "$thisKey")} {($ VSub_Name "$RESULT")}
                    )
                  ]
                  spids: [300 477]
                )
            )
            (Assignment
              keyword: Assign_Declare
              pairs: [
                (assign_pair lhs:(LhsName name:currentSexp) op:Equal spids:[487])
                (assign_pair lhs:(LhsName name:currentResult) op:Equal spids:[489])
              ]
              spids: [485]
            )
            (While
              cond: [
                (Sentence
                  child: 
                    (Pipeline
                      children: [
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (isEmpty_c)
                          } {(DQ (${ VSub_Name expressions))}
                        )
                      ]
                      negated: True
                    )
                  terminator: <Op_Semi ";">
                )
              ]
              body: 
                (DoGroup
                  children: [
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (first)
                          } {(DQ (${ VSub_Name expressions))}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:currentSexp)
                          op: Equal
                          rhs: {(${ VSub_Name RESULT)}
                          spids: [531]
                        )
                      ]
                      spids: [531]
                    )
                    (Sentence
                      child: 
                        (C 
                          {(variable) (Lit_Other ":") (Lit_Other ":") (LinkedList) (Lit_Other ":") 
                            (Lit_Other ":") (rest)
                          } {(DQ (${ VSub_Name expressions))}
                        )
                      terminator: <Op_Semi ";">
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:expressions)
                          op: Equal
                          rhs: {(${ VSub_Name RESULT)}
                          spids: [553]
                        )
                      ]
                      spids: [553]
                    )
                    (C {(evaluator) (Lit_Other ":") (Lit_Other ":") (eval)} 
                      {($ VSub_Name "$runningEnv")} {($ VSub_Name "$currentSexp")}
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:currentResult)
                          op: Equal
                          rhs: {(${ VSub_Name RESULT)}
                          spids: [569]
                        )
                      ]
                      spids: [569]
                    )
                  ]
                  spids: [512 575]
                )
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:RESULT)
                  op: Equal
                  rhs: {(DQ (${ VSub_Name currentResult))}
                  spids: [578]
                )
              ]
              spids: [578]
            )
          ]
          spids: [109]
        )
      spids: [97 108]
    )
    (If
      arms: [
        (if_arm
          cond: [
            (Sentence
              child: 
                (C {(Lit_Other "[")} {($ VSub_Number "$0")} {(KW_Bang "!") (Lit_Other "=")} 
                  {($ VSub_Name "$BASH_SOURCE")} {(Lit_Other "]")}
                )
              terminator: <Op_Semi ";">
            )
          ]
          action: [(ControlFlow token:<ControlFlow_Return return>)]
          spids: [-1 610]
        )
      ]
      spids: [-1 615]
    )
    (C {(assert) (Lit_Other ":") (Lit_Other ":") (report)})
    (If
      arms: [
        (if_arm
          cond: [
            (Sentence
              child: 
                (AndOr
                  children: [
                    (C {(Lit_Other "[")} 
                      {
                        (BracedVarSub
                          token: <VSub_Number 1>
                          suffix_op: (StringUnary op_id:VTest_Plus arg_word:{(isset)})
                          spids: [632 636]
                        )
                      } {(Lit_Other "]")}
                    )
                    (C {(Lit_Other "[")} {(DQ ($ VSub_Number "$1"))} {(Lit_Other "=") (Lit_Other "=")} 
                      {(DQ (debug))} {(Lit_Other "]")}
                    )
                  ]
                  op_id: Op_DAmp
                )
              terminator: <Op_Semi ";">
            )
          ]
          action: [(C {(variable) (Lit_Other ":") (Lit_Other ":") (printMetadata)})]
          spids: [-1 658]
        )
      ]
      spids: [-1 667]
    )
  ]
)